A roof top tent that allows you to still have some of your rack accessible? We feel like this should have been a thing a long time ago.
In any case, it's now a thing, and is being made by Thule/Tepui. It's essentially a regular folding tent, but it folds along the long side, instead of the short side. That means that the footprint on your roof rack is only half of other tents, but extends off the back and front. This is super great if you have a kayak or bicycle you want to pack with you.
From the Manufacturer:
Spacious rooftop tent sleeps two adults and folds compactly, preserving valuable space on your roof for bikes, kayaks and other cargo for your next adventure.