I'm new to the forum and this may all be a moot topic at this point, but if you look at www.rodbuilding.org you can find a huge list of suppliers on the left of the page.
I've built quite a few rods, and if you're going to have one built specifically for you and specifically for backpacking, I'd have to ask a lot of questions about what you really want. But, if you do some spin fishing as well as fly fishing, then my favorite is by far a composite of both.
The best rod I've built along this line includes a longer cork grip with rings to secure the reel anywhere along the grip. This allows the placement of a fly reel or a spinning reel and is also lighter than most reel seats. I then used a slightly modified Fuji new concept guide system to make casting as a spinning rod fairly efficient. The rod still works great as a fly rod.
I wouldn't recommend this build for someone wanting the ultimate performance out of either a spinning rod or a fly rod. But for those that want to carry only one rod into the backcountry and think they may want the functionality of two. It's a great build.