Dave, I reckon you'd never stop that think from leaking, the chassis is light and probably bent, and worst - it is a pop-top with similar weight figures to my full van that has a shower, toilet and cupboards everywhere.
You'd have to rebuild that one from the chassis up after you repaired/replaced the chassis. If you could snag it for a song, the fittings (lights, fridge, hot water, bed etc) could be useful in a rebuild.
We've had a caravan with a suspect chassis and it's not fun to tow. Just thought I should add that warning for anyone here interested in it that may be unaware.
