If you browse Amazon you'll find many mattresses available in 'standard' sizes AND in RV queen.
A few folks have taken an electric carving knife to their foam mattresses to shorten it. A few others went with the standard size and live with the inconvenience of the extra length.
We're tired of our mattress topper, too. Our TT bed takes a standard size queen mattress and I am shopping for a mattress for it. While searching, one of the things I've tried to determine was did people find a given mattress in a RV comfortable. Why? Because those are likely to be on a solid platform like ours, not a box spring.
I don't know the challenges you face buying a mattress in Canada. But, if you look, you'll find that 'short queen' mattresses are quite common and except for the length are made the same as standard length mattresses.
Sherm & Terry w/rescue Eydie (min Schnauzer) & Charley (std Poodle)
2015 Jay Flight 27RLS, GY Endurance (E), Days: 102 '15, 90 '16, 80 '17, 161 '18
2006 Ford F350 PSD, 4WD, CC, LB, SRW, Cmpr. pkg, Equal-i-zer 4-p, ContiTrac TR
Full timing: Some will think you're crazy, some will be envious, just enjoy the freedom!