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 adjustments.
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.