I'm on my first twin axel but I have never had a problem. I store with the Camping and Caravanning Club and use two storage facilities regularly.
Living in Weybridge, Surrey, I store at Walton on Thames in the summer as I can get to it easily and even pop in at lunch time as I work up the road if we are preparing to go away. I then take it up to Blackmore at the foot of the Malvern Hills for the winter as they are open all year round and we can use it as a holiday home in the winter months if I don't fancy towing due to the weather.
These sites even offer a tow in and tow out service so if we fancy a weekend end break, I ring up a couple of days before, drive up to the Malverns after work on the Friday and the van is there, on our favourite pitch (if available), waiting for us and we can arrive any time before 23.00. What could be easier?
There are a few sites that have a length restriction, usually due to the shape of the storage facility or the access but most of them are happy to accommodate a twin axel.
You can take a look here.....
http://campingandcaravanningclub.co.uk/ukcampsites/storageseasonalpitches/
Everyone I have ever encountered at the CCC have been superb and always happy to help or offer advice. They certainly get my vote.