hang in there man. make it exciting by finding new alternatives (x-c skiing, fat biking, etc.) ever thought about snow shoe racing? big in Colorado. wonder if that would give the legs problems? when the trail is powder, that is a ton of work and is kinda fun. racing on those things is an aerobic nightmare. strap fi to your back and go for a snowshoe hike in the powder.
ultra's on low mileage, even 100's can be done and are done successfully. my good friend john trent ran sd 100 this summer in 22 hrs. he runs 3x a week. tuesday and thursday a 8 mile run. on saturday 25-30 trial. nothing in between days, no cross training, nothing.
as for the shoes. you should know better then to think there are any magical shoes. people wearing hokas get injured just as much as people who wear anything else. I don't know though, those new hoka road shoes look pretty cool, especially the clayton for me. looks to have some support, unfortunately, it will be a cold day in hell before I can pay $150 bucks for a pair of shoes. that means i have to wait for closeouts 2016. I have been told that hoka is making a huge push to the roads for next year.