That existing 4' high loop is really delving into a rather gray area of the code. Normally the trap is considered the official point of transition between an appliance drain line and the house DWV system and in that case the manufacturer of the appliance may determine the required diameter of the appliance drain line which is determined by the volume and velocity of the discharge from the appliance. Generally the manufacturer will print a table in the installation guide that defines the size, length and permissible vertical lift of the drain line with recommendations to increase the line size if you need to exceed the length or vertical lift. That table will also define a maximum length or lift which is determined by the output pressure of the pump in relation to pipe friction loss or maximum vertical static head. In most cases the code will require that the appliance drain must be in an accessible location to permit servicing in the event that line should become obstructed. Whenever a drain line is permanently installed in the wall it is then classified as a portion of the structure DWV system and it would require that there must be a trap at the beginning of the concealed section of the line and the minimum permissible diamter of the line would then be determined by the DFU (drainage fixture unit) load value of the appliance or fixture being served by that drain. In the case of a dishwasher the DFU load is 2DFU's which would require a minimum of an 1-1/2" drain line. The plumbing codes also require that a dishwasher, washing machine, HVAC unit or a home water treatment discharge line must also be connected by means of an "indirect waste receptor". Under some local codes you could achieve the indirect waste receptor by installing an "Air Gap" or they may require you to install a standpipe on the trap and connect the dishwasher drain to a standpipe in the same manner as a washing machine line is commonly connected to a standpipe. (Some codes require all dishwashers to have an air gap, regardless of how the drain is connected. Check your local code.) Under the UPC whenever we have two common vented gravity flow drains connecting to the same vertical riser we are required to use a "Back to Back Tee" (4-way) however code prohibits connecting two commonly vented drains by means of a Back-to-back if one of those drains is receiving the discharge from a powered drain I.E. a dishwasher or washing machine. The discharge from a powered drain is required to be connected by means of a directional fitting (baffled Tee) and generally the baffled tee should be placed lower than the gravity drain. In your case the simple solution would be to connect the dishwasher to the disposal input port, providing that is permitted by your local code as well. (For reasons known only to the AHJ some codes prohibit connecting a dishwasher to a disposal input port..One code that immediately comes to mind here is the Illinois State Code.) Your screen name is Tom-in-Seattle so I am assuming that you are actually in Seattle. I am not certain but i believe your code is modelled after the UPC (Uniform Plumbing Code). If so the defined trap and waste arm size for a kitchen sink is 1-1/2" but under the UPC all vertical risers and drain lines serving a kitchen drain must be a minimum of 2" pipe. You may use an 1-1/2" pipe for the vent. There is some question about whether the length of the horizontal offset on the vent in your attic would pass, but I doubt that it would even come into play unless you happen upon a hardnose inspector that is really intent on finding a problem.

In many countries, Switzerland being one of the first....vented dryers are illegal! Of course if you have one, you may continue to use it, but no new vented dryers have been sold there for several years. Miele cites safety reasons, for no longer selling vented dryers to residential customers. Condenser or heat pump dryers can contain a fire much longer, than most vented models. I used a ventless dryer years ago in Sweden and Germany...and OMG, I too hated it. Hot, slow, moist, wrinkled!!! They are so much better now, and Miele, Electrolux 24" and I believe Blomberg have reverse tumbling whilst drying and cooling down. This drastically prevents & minimizes wrinkling, sheets and blankets balling up and moist/wet spots. 40 years of vented drying.....and I have been ventless/condenser for many months now, and I love it for the most part. Yes, it takes longer, but it is not too bad. Most loads are done in 60 mins of less, and that includes about 15 mins or Cooling Down.

Rerod, it seems like you're not finding the information/opinions you need here to help you make your decisions, and it sounds like you ran into a similar situation on the manufactured housing board you tried. I think that's because as much as people really want to help, you are dealing with a niche issue that most of us haven't experienced. We welcome new and different dilemmas, but you may be frustrated because most of us lack the expertise you need. I wonder if you've looked for any forums for the homesteading/back-to-the-land/prepper lifestyle. That lifestyle might be a little more hardcore than you're interested in, but I would bet those folks have wrestled through a lot of the decisions and issues you are currently considering. I wish I knew of a forum like that to recommend to you, but maybe someone else here does? If I were searching one of the places I'd look is Reddit. There are subreddits on just about everything, and I wouldn't be surprised if there's one for homesteading. Anyway...just throwing that out for your consideration. I wish you all the best with getting settled on your property, and I hope you'll share your progress with us as you go along.

Thank you very much. I figured as much, but wanted to be sure. I also do not mind the height difference as I'm 6'3" and would prefer it higher than a standard sink. My back always hurts when hunched over a sink for a while, and this sink will actually get a bunch of use by myself.