So some internet searching led me to this cover, the largest non custom RV cover of what appears to be decent quality large enough in length to fit a seneca.. height was the question.. So here is what it looks like on a 36MS, like high water britches. but.. in going to use it anyhow with the lower tied out away from the coach to prevent chaffing.. it will work for my needs under the RV shade to prevent droppings and reducing surface dust.. I did speak with them and found that they make a Class A cover that is the same material and cost (about 300 bucks on amazon shipped) that has a sidewall height of 120", this one is 108".. so that one would be proper height but youd have some additional front cap material to figure out what to do with.. not sure which is the better of the two options.. so.. this is what this cover looks like on a Kodiak chassis Seneca.. I dont think i'll trust it in a strong wind without additional tie downs.. it would probably do some decent damage if left to flap away.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Cheers..