Should work, but it won't be warm in there (not just now anyway!)
I often think that some curtain sides around the opened tailgate would give some useful extra space (Nick are you listening?).
At one time I was considering having the lower bed pushed up against the front seats and modifying the parcel shelf area so that the free floor space was next to the tailgate. One could then just slip into the tailgate tent to do one's business .... or not.
Another point worth a thought is that the lower bed in the Cali is (I think) 6' 6 " long, more than most conversions or even coachbuilts, and more than a lot of people need. If the rear parcel shelf was shortened and the bed not pulled forward so much another 6" or so of space could be gained, a lot in a Cali, useful for the loo ... At one point last year I did make a replacement shortened rear parcel shelf; like a lot of things it never got got finished and the bits are in the garage awaiting further construction ...