When I was writing gear reviews I tested tents from all the major US firms and quite a few European makers (VauDe, Hilleberg). A mountaineering tent has to stand up to extremes of wind, cold, and snow, and condensation that you seldom encounter on a river trip. Plus you have to carry it on your back.
On river trips, you camp in sand pretty often: hard on fabrics, pole joints, and zippers— the trick ultralight stuff wears out fast. Since your boat carries the tent, it doesn't have to be light— just rugged.
So my favorite river tents are relatively cheap and simple. For the Grand Canyon (sleeping alone) I took a Eureka Zephyr XT, a solo wedge or X tent with a peak-vented fly and big opposite openings for super ventilation even zipped up for bug pro. Five-minute pitch. As I recall, the Camp-Mor price was about $125. After six years and many trips, it's holding up well.
A few years ago, Eureka sent me a Zeus 4EXO to test. It's a single-wall design of coated (not breathable) fabric with excellent venting options, ample room for mate & dog, and a big vestibule for gear stacks or foul-weather cookery. About 9 lbs., less than ten minutes to pitch. Nice not to have to piss about with a separate fly. The pole setup is stout— it's stood up to a couple black squalls when you couldn't see for blowing sand and cottonwood limbs were snapping and raining down. Don't know the price, but estimate about $225.
Not sure what the current models are, but expect you could get a nice river tent for $250 or less.