Going through the same thing right now with my left handed X-bolt, but I am heading the lightweight route vs long range. Still undecided if I am going to jump ship entirely or double down on my single rifle commitment.
McMillan can do stocks for X-bolts, though just in a few models, and have been great to work with. I believe you can add on new bottom metal and DBM if you want, though that's adding even more to the final bill. Even in a carbon stock I think that the replacement won't be much lighter than my factory wood stock. You can definitely go heavier if that's what you're after.
In my research I also tried Grayboe and they have some interest in offering X bolt stocks, but it's not at the top of their list with no real estimated timeline. Boyds is the only other option I have found.