I've never seen an out swinging door behind and out swinging storm door. I don't know if it would function.

Lilac, welcome to the group. If that doorway is 70 inches WIDE, that will be too wide for a tension rod to span. However, you might think about getting a SHOWER ROD, WHICH IS ABOUT 6 FEET LONG, and a diameter of more than one inch. You could even put a sexy shower curtain on that rod and also hang the canvas drop cloths on the same rod. Shower hooks are great, or even the set of shower rings. I have used the 9 strand 100 pound stainless steel picture hanging wire to hang curtains. In my case, I bought a 100 foot roll of it, but you can get it in lengths. OR, you might go to a place like RESTORE which is a Habitat for Humanity resale place. They have many many doors that came off closets, like the bifold shutter doors. I've found many nice doors that way. If you cannot screw them to the woodwork, and you want to take any purchased items with you when you go, think about attaching the doors to a bookcase or entertainment center at the side so you can open/close the bifolds. It is possible, depending on the size of the room and the location of that wide doorway in it, that you could position an entertainment center in front of the opening, and leave only enough space to have a 28 inch entry to your bedroom. I'm assuming that closing the passage to the kitchen from the dining room will still give you another entry to your kitchen? Quite an interesting question, and you can definitely make your choice attractive. Also note, I use the regular canvas painter drop cloths, available in all sizes, very washable and quite durable, as slip cover for my furniture, bird cages, curtains, pillow covers, bed throws, and I can paint on them and make them tough and hard for small rugs at the doors. Very washable, very durable, and the cheapest thing you can buy. Sort of the color of oatmeal denim, and as durable as a canvas bag.

Thanks for the replies so far! Just to clear things up - The "Den" is also going to be an office - we need two. The idea of making the dining room into an office is about function over form, and actually using the space instead of wasting it. We've had guests over 0 times in the last 15 years. We've owned 6 homes in those years (including the one we are in now) with formal dining rooms and not used the dining table once. There is just us two - Our family lives 3000 miles away - and we are busy professionals - in retirement we will be at our country club for food/entertaining.. As is - we eat in the family room 99% of the time and only use our nook table for holidays... The large counter in this build would replace functionality of the nook table. The patio/pool area will have an extension with a fully screened in cage, and be a gathering space with tables/chairs - though where we live, it's miserable to be outside 8 months out of the year - so it's never used. That's our life - it's not even close to the same for everyone - which is why we wanted to make the conversion temporary - so it can be converted back for resale.

If you don't want to actually wall off part of the living/dining space as a bedroom, then at least claim the entire wall between stairwell and exterior patio door wall for your "bedroom". Set your bed and your wardrobe and your chest of drawers against that wall. If you don't already have a twin bed for yourself, choose a quality metal twin bed frame with castors and without headboard of foot board -- one that, with appropriate pillows/bolsters, could pass as a day bed ... one that appears to be and could be used as seating; however, do NOT let anyone get in the habit of using it as seating or you'll end up with the side edge your mattress being worn and sagging in an uncomfortable way. (Aunt had this issue with her day bed when I was a child.) If you have any difficulty with physical activity, do not skimp on your mattress and box springs -- get the best of both and have the height of your bed be what you can use comfortably, such as swing your legs over the side and stand up rather than needing to climb up out of the bed. (Been there; done that -- too low is not good.) On a tight budget, consider checking with Habitat for Humanity Restore Store for good used wood furnishings -- wardrobe and chest of drawers -- and even the metal bed frame. Would not upholstered furnishings or mattress used. You might also try checking with other local charity sponsored thrift stores and/or used/antique/consignment stores.