Do you mean pitch a tent on shore from their RV? Or come along with you in the boat and then camp on shore?
If the former, there aren't that many places I know of to access the shoreline from a road RV. A few, such as Lone Rock (near Wahweap) and the campgrounds at Wahweap and Bullfrog, but not many (or maybe not any) in the bulk of the lake.
If the latter, I have seen many people camped on shore from boats all over the lake. I'd want a zip-up-able tent to keep the various creepy crawlies out while sleeping (including mice, of which there are plenty). But there are lots of nice sand beaches to camp on right near where you would beach or anchor a C-Dory (no tides and the river level doesn't typically fluctuate daily).