We store outside under a cover in the Southeast. We occasionally have roaches, but if you do a great job of keeping the food out they will have nothing to attract them. Also, don't heat or cool the coach (let it be the same temp outside as inside) and you'll reduce another incentive fro critters to set up house.
We park ours in a gravel area and keep the surrounding are free from grass, weeds, and leaves. I'd be hesitant to park in the grass and just let it grow or and/or die like some do.
I sometimes sprinkle some Sevin dust around the tires in the summer. I think it helps keep ants from exploring, but I can't say for sure.
Mice have been the biggest issue. They love the engine bay of the Ford V-10. This can be a problem even with garage or covered storage. I check frequently for signs and set a snap trap if I see anything. I catch _maybe_ one a season.
All in all, the convenience of having the coach at the house combined with the expense of a full garage make covered outside storage a fine choice for us.
