Gel / memory foam TOPPER that can be returned?

Looking for a quality topper for the latex layers I already have. I’ve tried several through Amazon but all are not high enough quality and squash after a few days. I purchased through Amazon just to try to find short term relief and knowing they can be returned. I love the feeling of the gel foam most. I do NOT like latex at all and regret purchasing an entirely latex mattress. But luckily the mattress is customizable so I can add/change layers. If I don’t find comfort soon I’ll be selling it off entirely and starting over.

I’m 5’3", 125ish lbs, side sleeper, history of upper back, neck, shoulder injuries. Thus I need support and pressure relief in the right places.

I live in Canada but could purchase via U.S. as long as returns are allowed.

I’ve searched the confusing forum threads and haven’t found what I’m looking for.