I haven't had a problem (yet). But I'll have to double check, but I think the BBQ bottle used the same (external thread) fitting as the Forklift tank.
So you *should* be able to screw on the BBQ tank, turn it upside down (to get liquid) then take it easy as to not freeze the valve.
If you need to make an adapter hose a local Propane or Forklift supply should be able to help you. Or try e-bay.
I've been curious to find out how long a portable "Coleman" tank would last. Easier to stash a couple of those around the rig and make a "port" on the dash or something to be able to limp out.