I used a lot of Sonax Net Shield spray in the Pacific Northwest and it had great durability on vehicles that sat outside 24/7 in the rain, and then later, in the snow..
I never used anything else underneath it or over it..
It wants to be a little "grabby" the first time you apply it, but once it`s on and dries, it plays nicely...
I once paint corrected a more than gently used BMW 5 series in Jet Black; corrected with Menzerna, then the Sonax, and the Boss parked it out front of the Shop for a year.
It looked great after 1 full year...It got dirty, then it rained, snowed; rinsed off all the dirt, start over..
Dan F