I haven't pulled back the caulk. Getting in the space won't be difficult. On the outside edge of the tub, the deck space is slightly over four inches. On the faucet edge, there is no decking; the tub butts up against the wall. On the back end of the tub, there is about eight inches. On the final long side, there is a "garden" type window centered with the tub, which is 25 inches deep and 48 inches long. Basically, it is an extension of the deck. I will try to post a picture once I figure out how to do it!

Since it's on you, I'd go after Kohler again. Simply start anew. Get a written diagnosis from the second evaluator. Send it to Kohler and start a warranty claim. Pretend it's the first time you've called them. 1) Tub was purchased from _____ on ____. 2) Tub was installed on ____ by a licensed plumber in accordance with the manufacturers instructions. 3) Within days of the installation a squeaking noise was heard. 4) You had two people come out and diagnose it as a delamination. Include the written report from the second person. 5) State what you want: A new tub. I'd also contact the point-of-purchase. They sold you a bad tub. As a follow up to the initial phone call claim with them, include the written delamination assessment made by the second evaluator. Send them the same info noted above. Written letters and emails start the paper trail. Phone calls are great to "shake the tree", any time you talk to anyone note the day, time, person you spoke with, case/claim number if they assign you one, and take brief notes of the conversation. Kohler is usually pretty good about claims. Best thing I can offer is to be calm but firm in your conversations, be businesslike. And keep good notes. When I've dealt with things like this, I've kept my notes in a document file on my computer. If I talk to someone new, I'll email them the file while I'm on the phone with them. Depending on the situation I might password protect it or convert it into a pdf file before sending it so it can't be muddled with by the recipient. No, I've never done or had done a gel injection. I've never heard of it being done. Not saying it won't work. But I've never had a tub delaminate! As a bit of a last resort, talk to your GC. If Kohler is claiming the tub was installed incorrectly, that falls back on him and on his plumber. You might be able to get separate letters from the plumber and the GC saying that the tub was installed IAW the manufacturers instructions and that they agree with the evaluation that delamination as a result of a manufacturing defect are the cause of the squeak. Again, all that is based on the tub having been installed correctly. ie, it's not a drop-in tub that is being supported by the rim instead of by the base/feet for example. Again, good luck.

I love my under mount tub ...it is very comfortable. The back slopes; I never have banged my head on the ledge. I use mine daily - I prefer a bath to a shower. An under mount gives me a place to set my morning coffee without spilling it on the tub ledge and plenty of room for the morning paper or my Kindle. I am short, so I wanted one that wasn't too long - a 60" works great for me. I've never understood free standing tubs - where would you put everything? And a drop-in would have an uneven ledge and I'd spill my coffee.

This long and narrow bathroom reminds me of the one I grew up with in Brooklyn. It had the same problems you are facing. I highly doubt there is a radiator in this bathroom. The OP can comment if it exists or not. The large diameter steam pipe in the corner is a typical set up for bathrooms in old buildings. There is probably one thermostat controlling the heat for the entire building. The apartment above does not get to set its own temperature. How warm you apartment is in the winter is determined by what floor you live on. I agree if this is the only bathroom then it should to have a tub. I am not sure if re-configuring the tub is going to lower the resale value on a $1M+ coop in NYC. Putting up the wall between the tub and the sink makes the shower more functional. But it will make the bathroom look smaller and block some of the light from the window. I still think if you are going to move the tub the something like this one at Home Depot could work. It is 6 inches shorter than a normal tub. You will need 54 inches from stud to stud which may be possible once the plaster and lathe are removed from the walls. You could install the tub 8-10 inches away from the window wall. A shelf could be built between the tub and the wall and covered with tile. That becomes a place to hold your shampoo bottles and soap dish. Most of the steam pipe would still be exposed and will keep the bathroom warm even with the shower curtain closed. The shower head and controls stay on the same wall. This will open the space to put in a 36 - 48 in vanity with a granite counter top and a wider medicine cabinets and better lighting. That will give you ample storage space. Something that was not an issue when this bathroom was laid out 100 years ago. Have you asked any of your neighbors if they have remodeled their bathrooms? It would be helpful to get ideas and see how they dealt with these challenges.