Storage is very simple and there really is no right from wrong on this issue with the exception of moisture. There a many different ways to store your units and many opinions about one way being better than the other. We suggest using the following examples and find which ones work best for you.
First of all, your units should receive a thorough cleaning and inspection before they are put away for the season or for any length of time. Each unit should be completely dry inside and out before you do so. The webbing, straps, threads and netting all tend to stay wet or damp and do not dry as fast as the vinyl itself. In this case its critical that these components are completely dry before storing. The damp/wet material can bleed and discolor the vinyl, cause mold or mildew, or start to rot and decay. After a few months of storage this would not be a pleasant situation to discover when opening the unit up for the first time.
A lot of people prefer to store their units on pallets offering reasons such as making them easier to move around if neccessary, keeping them off the cold concrete is better for the material, but the most obvious reason is to keep them off the ground in order to avoid moisture or water should the storage location leak, flood, etc..
It has been suggested that using dessicant packaging, that absorbs moisture should be used for long term storage however no study or tests have been conducted so conclusive benefits or disadvantages are not readily available. In such a large item as an inflatable, it may be cost prohibitive. If a unit is dried properly than this should not be an issue.
If you prefer to use storage bags make sure the bag can "breathe" so that moisture can not form and be trapped inside the unit. This same reasoning applies with wrapping the units in tarps, plastic sheeting, etc.. If moisture forms, it will likely persist and again you end up with an undesirable result.
There are a number of sprays, tins, pellets and other products designed to keep rodents and small animals away and if you use anything, make sure it does not come in contact with any of the equipment so damage from chemicals contained in those products can be prevented. You'll also want to avoid anything that emits an aroma, so the unit does not get permeated with that smell. No one wants a moth ball bounce for a rental.
Temperature range does not really affect the storage properties other than extreme heat can cause excess moisture, and extreme cold will make a unit very hard to handle should you need to use it for an indoor event. In that case allowing it to warm for about half and hour to an hour would decrease the unlikely chance of the unit becoming too brittle and cracking from its cold storage. To recap, simply clean, dry, and allow it to remain moisture free and you should be perfectly fine.