Bear Creek Canvas is the best known canvas replacement company.
they are mainly just popups but i've know they do some hybrids also.
you also could contact the tent ends manufacturer.
should be a tag along one of the seams of the tent end.
my '07 Roo had its ends made by TJ Snuggles, in Indiana.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC