If you store the kayak upside down, which is what Hobie recommends anyway, and off the ground, you should not have a problem with critters. In my area I have field mice and feral cats that have taken up residence in various locations but never in the kayaks that I have mounted on a T stand that has 2 kayaks on their sides in J hooks and a third that is on the top of the T and upside down.
I used 4x4 pressure treated lumber set into post holes that I filled with concrete (post mix) and 2x4 cross pieces topped with closed cell foam and it supports the boats with minimal foot print and is never going to blow over or get knocked over. I bungee a tarp in place over the rack to keep the boats clean.
Indoors a couple of sawhorses would also work with the boat upside down. I also like the Suspenz products which are very well designed and constructed. Not the cheapest solution but their racks and stands are a one time expense. I have a set of their large workstation stands that I use when doing rigging on my kayaks.
http://www.suspenzkayakstorage.com/