Float Tube Bladder Storage

After the surge in popularity of float tubing over here in the UK, I
shipped in a Caddis Navigator II from the USA.

I have used it most of the season and now wish to store it for a
couple of months as it is currently hanging up in the garage taking up
space.

I was wondering if there was any advice from the USA for storage of
the bladders as they came "flat packed". I'm just concerned that
deflating them may cause the bladder walls to stick together due to
moisture etc contained in the bladders as a result of pumping them up
both orally and with the foot pump. The bladders are of a plastic
consistency and as such I would hope they would not deteriorate so
easily (as rubber does when stored).

The only other solution is to leave it permanently inflated !

Advice would be appreciated, many thanks.