We have a Puck L 225GT which also had the spare wheel under the seat at the front. We didn't like the intrusion into the floor space and needed the underseat storage for something else. We've removed the spare wheel and put this in the boot of our car whilst towing. Once we've arrived, we take it out and lock it outside, around one of the wheels, pushed under the van out of the way. It seems to have helped slightly as our nose weight was a little high, and now acts as a separate security device, in addition to our wheel clamp.
We removed the boxed out section and replaced with a flat panel, inline with the rest of the seating edge.
Hope that helps.
Andy