I've contacted both EuroVan and Breeze to compare so i'll report back once I have responses from both
After discussing with my wife, we feel that having space for chocks / windbreak etc would be better. When we hired, we didn't feel that we were short on storage space, but did have to keep the windbreak in the rear passenger area which wasn't ideal. We'll put the money we save towards other options e.g. towbar prep.
We have also decided to skip the comfort mattress. My wife had a terrible time getting a good nights' sleep due to the mattress and from what I can tell from other threads, aftermarket mattresses seem to be much more comfortable. I'm interested in the Sea to Summit since it got good reviews. Will probably wait until I receive the van since I can always return if no good.