This is just my preference: When we covered the 5er for the winter I would buy a farm tarp to cover the 5er, and about twice the number of elastic cords to hold it taut than the normal number of eyelets in the tarp. I added eyelets about 2' apart. The A/C unit, antenna, and vents hold the tarp up enough for ventilation, but if there is a sag in the tarp, I put a cheap beach ball under there so water cannot pool. If any water penetrates the tarp, it will be little.
Some folks complain about the tarp chaffing the RV from wind, but I've personally never discovered such places on any RV I have ever owned. Exactly the reason for using twice the number of elastic cords.
I guess this makes me a cheapskate, but $70 for a tarp that lasts for 4 years, and $10-$14 for elastic cords vs hundreds for a commercial cover is money in my pocket.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"