Wow - sounds like a beast!
Get a few friends to position the
battery i'd say. so you dont break your back
I've got a big 12v
battery in mine as a 2nd
battery, it was used for a few months in a coach to power the accesory equiptment like the A/C, heater blowers and other stuff. It's not a leisure
battery by anymeans - its rated at 660 cranking amps. But after a full weekend of lights/radio/dvd/tft/charging phones - it was still showing full charge!
Anyway, not sure the setup of your van - if its a self build or not, do you have a designated spot for it already where your wiring is?
As its very weighty, obvioulsy sit it on the floor, make sure its got some sort of tray underneath, and even a
'battery mat' as if it leaks the acid will eventually eat away anything thats underneath the
battery - even metal!
Make sure its held down well - two long bits of threaded bar from the floor of the van and a strip of metal to act as a strap over the top of the
battery would be good, with the relevant nuts & washers installed on the bar itself. Kepp the metal strap away from the terminals though
Aslo - due to the weight, i'd guess it would be ideal if you could get it sitting over an axle.
You could also get a
battery box and screw/bolt/strap it down and put the batt in there - if you can get a box big enough?
A bit like this - but other people sell different sizes:
BATTERY BOXES | Marine Super Store
Hope you get sorted