Thanks Scotty, It'd be good to catch up again.
Here's a bit more detail on the mounts.
I machined up some steel threaded bosses. These slot into a hole I've drilled into the chassis rail and will be welded in place. They are just tacked at the moment while I set every thing up.
Here you can see the mushroom shaped bushing that goes through the rubber. There is a 10mm cap screw through the center that clamps the bush against the chassis rail. This can be done up tight and and the set length of the bushing stops the rubber from being crushed. I will probably lock wire them as well just in case.
Just got to tack weld the bracket to the tank now and then pull the whole thing out and weld it properly.
Cheers