I'm sorry that nobody has replied to you earlier: most unlike the JRA!
Choosing light, UV-resistant canvas isn't that easy, and it's not made any better by the fact that so few boats are out in strong sunlight for any lenght of time. I've been happy with my Weathermax up to now (2+ years), although an acquaintance complained that his had deteriorated badly in the Tropics. There is a lighterweight Weathermax available.
As to webbing.Don't be tempted by polypropylene which deteriorates very rapidly in sunshine - and isn't particularly strong. The black, polyester webbing that most sailmakers use lasts for years. I have always found sailmakers incredibly obliging people and if you go to the one nearest to you, I'm sure they will order you a reel of webbing so that you know you're getting the right stuff.
Hopefully, with this reply taking the topic back up to the top, someone else will chip in.