In my experience it's extremely important to work
with someone local for most canvas projects, certainly for an enclosure. They need to measure and make templates, then fabricate, install, then make adjustments. It's not unheard of for them to make more than one trip to the boat
For simpler projects they can work
off of old canvas, but you're asking for trouble with a full enclosure.
I'd suck it up until March and work with someone local.