I'm kind of in your same situation but somewhat less extreme. I own 3 pairs of Gustin denim and though they are wearable, the thigh cut is an issue for me. FWIW, their chino fit seems to work better.
Point is, I have stopped sinking money into jeans from Gustin, but as I've explored their other offerings, still spend plenty there. I agree with others that Gustin's value proposition makes no sense if you're having to make so many alterations.
In general, I wish they would design more athletic cuts for their stuff. Their collared shirts don't have much taper and require me to have them taken in (but I pretty much have to alter shirts from any brand that isn't MTM so this is just reality for me). Same is true for T shirts. I've yet to find a brand that makes high quality goods that are cut for someone with a V shaped upper body and larger thighs.
The chinos looked great on paper so I ordered a pair in olive duck canvas. Unfortunately what arrived was way out of spec and had to be returned.
There was a joke on this thread some time ago saying 'people that fit into the shirts won't be fitting into the jeans'! Tapered shirts are rare. Banana sells some that are OK. Express does too, but those are crap.