The longest undersea power line is 580km by comparison, so that' not a huge issue.
A straight path from the Mojave to the Gobi desert is 9000 km directly through the Bering Strait.
Is it possible to make floating Solar panels?
Anything is possible. We could power the entire US if we put a large collection of panels in the desert. Surprised there aren't self cleaning panels yet (maybe there are) :).
Yes, but why? You've got all the maintenance headaches of wave power with none of the benefit.
It might be useful for above-ground water reservoirs. They sometimes float balls on their surface to reduce evaporation in hot environments (especially ones with a breeze). If you could do the same with large arrays of floating solar panels, you could reduce evaporation and get energy out of it at the same time.