What kind of plane is this? 45 degrees is a huge amount of travel, even for a 3D type plane.
As for servo resolution, it's a good thing, but not something to stress out about. If you set up the servos with the standard 100% of travel and then adjust the clevises to get the recommended throws you need, you'll be fine. Back when radios only had 256 positions for the servos to go to resolution mattered. Now that it's 1024 on most radios and even 2048 on some, it really doesn't. What does matter is torque and gear wear, which having 100% travel helps with tremendously. But if you wind up at 90% travel when it's all done, there will be no difference at all in the flying characteristics of your plane when it's all done.