This is how I did mine, very similar in the way Flyerncle has described,
I used 3mm plate to bridge the end of the chassis & as you can see, used 4 bolts with nylocs underneath ( same idea as the upper roll bar mounts ), so the whole roll bar is removable after undoing 16, yes 16 bolts
...if that lot gives way I,m a gonna anyways
excuse the untidy wiring, this pic was taken ages ago.
cheers
andy