My two pennies,
I bring a ladder like TM with me always in the cab. In the winter, if snow is forecast I set my alarm every two hours or so. if needed, I climb up and sweep the roof off. Will be adding some blocks to reinforce the sides, my roof is a little longer than standard, but feel like this is mostly for peace of mind.
Not worried about getting up and down, because well its part of the experience or camping in a glorified tent in the winter.
BTW, I mostly camp in the rockies during the winter but do manage a few nights out in the cascades.
Worst case would be to sleep down on the floor,(no bench or dinette) and I will do that if I am just catching a few zzzz's.