Yes fully unlined jackets are uncanvassed. if you don't have much to fill out the jacket out (not a problem, just saying) it may not look as good and you may want to get more structure in the jackets, in which case you can get the partially lined ones which will have the canvas in front and be lined there as well, with the lining gone in back.
the durability will not be the same as a fully canvassed one, but it can be nice to not sweat your ass off. i assume that's the thought process?
Perfect, thanks. Exactly the thought process, summers are typically exceptionally humid.