I was in a similar boat a number of years ago with the downstairs bathroom, what with no access panel and all. Based on that experience, which was probably 10 years ago or so at this point, I'm pretty much all in on Sharkbite fittings. That, or if you're using copper you can use those crimp fittings that are all the rage these days. I'm good at soldering, but also: fuck soldering. Depending on the orientation it can be a real pain in the ass, and sometimes there just isn't enough space to work in to feasibly do what you have to do with solder.

I was initially skeptical of the longevity of Sharkbite fittings but I've had a pair of 'em in my wall all this time without any incidents to report.

Mine was a mega builder's grade three hole arrangement for which rebuild parts are flat out not available and which was largely apparently made from chrome plated plastic. So I replaced it with a similar but rather nicer assembly that's at least from a company I've actually heard of (I think it's a Delta, but don't quote me).

When you're hacking your access hole in the wall, take measures to avoid also cutting into the pipes in the process. Ask me how I know.