Do you leave this on the vehicle all the time or just on a trip?
Only on the rig during a trip as it is soooo cool someone here in Phx would steal it otherwise.
Is it ok to leave it on as far as UV problems? (I realize nothing is completely safe against sun exposure, but some things last much longer than others...)
It isn't UV damage but more of an aging effect you might see over time...and I have had mine on quite a bit since I got it last Nov and the brutal Az sun hasn't hurt it at all.
Do you use a plastic liner/trash back inside, or just throw the trash straight in the bag?
Home Depot 3mil Contractors bags are my choice, heavy enough to not tear when I pull them out to toss away. Also make a survival shelter, body wrap and other handy uses if needed.
How water proof/resistant is the canvas with the flap closed?
As I use a bag inside mine I have not worried about that at all.
The only other thing would be to make good use of the other pockets to store your bags, some gloves and get out/take pics and send them to Dave & Yoshi
cigar smoking, wilderness first responding, ham talking night nurse who is overland certified and a fellow of the Royal Geographical Society.....
now everyone say "so what where have you been lately?"