Dewman1945;
Please don't take any of my questions, advice, or even photos of my work, as criticisms of yours. They are certainly not meant to be.
Most home model railroads are individual efforts and, as you rightly say, the only one who needs to be satisfied with your work, or the materials you use, is you. I have also used white bead board when it was all I could find. You work with what you can get.
Also understand that the photos I post are things on my
seventh model railroad, not my
first. I have 50-odd years of experience as a model railroader that got my work to this point. If you had seen some of my early efforts, you might see that they were not as good as what you're doing now. If you look through the, "My Layout" section of this forum, you'll see a whole lot of very basic layouts that are making their owners very happy.
Yes, I have tried the aerosol foam and it did not work well at all. The stuff is so incredibly sticky that a large version of it was once considered by the sheriff's department as a non-lethal weapon to capture, and immobilize people! It worked, sort of, but it took hours to extract the suspect from the foam!
Once on the skin, it won't come off with anything short of sandpaper. It can also only be used in shallow layers, or the inside won't harden. Its shape is also random, and impossible to control. I definitely do not recommend it.
If you look at my photos of linkages and front panel controls, do you think that is something you might want to adopt since you're in a wheelchair? I'm assuming that going under the layout is not a viable option for you. It isn't for me either. I'm not in a wheelchair, but I do have enough of a disability to be virtually unable to crawl under a layout without a whole lot of pain. I also can't stand still very well, or for long. (nerve problem in my lower spine) That's the reason I moved a lot of gear to the front of the layout where I can get at it, sitting down. Another thing that might make things easier is to build your layout in sections small & light enough to be turned upside down. This makes traditional "under-the -table" chores like wiring, and mounting/adjusting switch machines, a whole lot easier.
Keep up the good work & keep having fun;
Traction Fan 🙂