I had a 24'x 24' canvas tarp over my carport that shrunk down to 21' x 21' in about 2yrs...It held up well as far as material but shrunk like a b!tch....All sunshine here never bad weather...

Is there something better that won't shrink but holds up like real canvas?

Someone with actual knowledge will chime in here I'm sure. Until then, I have "canvas like" material on a wood frame on an outside swing. After many years it developed a tear, so I thought I would put a heavy duty iron-on patch to extend it's life a bit. Low and behold when I hit that "canvas" with a hot iron it partially melted!!! So, it has some synthetic plastic like material within it's make up and shrinkage over may years was not noticed. Good luck.

try looking for semi trailer tarp shop

Find a sail maker.

if covering the top with a suitable material cant be done for what ever reason,you have a tarp just start slowly installing a better top useing tarp till done

Try Sunbrella. It is very expensive but really good stuff. We use it for boat covers.