But seriously, don't leave your skis on a rack naked. The road salt will buttfuck your bindings and edges so fast it'll make your titties twist right off.
I honestly would put them inside. Naked racks are the worst for the long term health of your skis and bindings. Salt degrades plastic at an alarming rate and even corrodes stainless steel and strips lubricants like none other.
I would seriously recommend wither a roof box or putting them inside, but I suppose you could get MacGyver on it with some tape and saran wrap or something. I've seen ski bags lashed to the roof before, but that just seems exceedingly gaperish to me.
I just put them inside my car though, and put my dry bags on the roof if space is an issue.
No it really does.
My brother put his skis in a clamshell for a ride home, then just leaned them up in a corner for two weeks came back and the skis had to be reground there was so much rust on the edges. Upon further inspection the internals of the bindings had surface rust on them as well. Now this may not blow your shit up overnight, but it's not good for you skis and i don't know about you but I really don't want rust on my DIN spring.
So yeah, if I'm driving in shitty weather, I put them inside. Obviously if it's nice out it's not an issue.