I’d say build what you want to build, but having experienced that environment as well as been down a similar rifle path I have a few things to offer.
1. I agree on the can above, the OG or an airlock ZG are going to perform a lot better than tbac u5. Cheaper too I think.
2. Folders are cool but I think barrel length is also extremely important. 7PRC I’d say 20”, or 6.5 PRC in an 18” would be even better.
3. So for a chassis - 7PRC can rough. The “tuning fork” thing is very real with metal ones, at least it was for me. So I’d lean poly or carbon there. HNT 26 if folding although I really like the simplicity of the XLR, just not the recoil impulse. It’ll be less effective than an above bore butt pad stock, especially in a magnum, for follow up shops.
4. While PRC would be cool, if building “light” I think that’s a creed all day. Shoot the right bullet to maximize killing effectiveness and you’ll be set. I personally enjoy lighter/handier/smaller recoil with shorter barrel, and spend some weight on your optic. I would not build a magnum 8lb or less, I’d be 9-10 with 7 PRC. I’ve got an 8.5lb one and I can shoot it well (but follow ups are really hard), but my 6 creed enables me to run circles around it accuracy wise.
5. Concur on FFP scope.
Again if custom - ignore everything and just do what you want! Not sure on budget but that Alterra X rifle that breaks down would be super cool for a 7PRC or similar build.