Scamp just uses the tray and holder, and screws it onto the top of the frame with self tapping screws.
If you get one of those kits, you have the option of using your current regulator/hose and just switch to the other tank manually, or purchasing a new double hose regulator that gives you the option of automatic switchover.
I had thought about moving my double tanks further back, and then moving the
battery in front of them but never did.