What installation method will you be using? Full spread or perimeter install?

Most sheet vinyl that is adhered to a substrate can be installed 'net' to vertical surfaces. you can install it with an expansion space if you want.

You may want to rethink using silicone sealant; it can attract dust particles and look dirty most of the time. Also, it is not easy to use.

If I am understanding your question correctly: There is a long/thin piece of material that you use- you put it tight up against the tub, then the vinyl goes on it, and it folds tightly over it. It then does not 'move', curl up or shift in any way. I am sure you have seen these. there are cheapie ones at HD and Lowe's, and thinner, nicer ones at the nicer carpet stores. they are very inexpensive. I have actually seen baths that were in the 'Parade of Homes', supposedly built by top builders that didn't even have these. I am sorry I don't know the proper name. Myvinyl has been in my downstairs bath for about 7 years- it looks wonderful, with no telltale water damage of any kind where the vinyl meets the tub.