well you could repair/fix the lines on those water cooled rigs, but you'd still need to run water/coolant through it to cool the torch. You can look around on the web and see that watercooled torches have been in use for a long time, even without recirculating pumps/coolers. So you could salvage a setup for home/shop use and not need much more, but you won't want that setup on your truck.
Now if it was up to me, I'd find me an air cooled rig and go. rember the K.I.S.S. theory. I've got a Bernard watercooler and torch setup for my big Tig machine at the shop, but I don't paticulary care for it. I use a 17 or a 26 air cooled torch, just like I would in the field for no more Tig work than I do.
Asfar as length goes, your Tig rig can be asfar as your leads will reach and you want to tote your sheilding gas bottle, or you just just extend the hose from the reg to whatever length you need.
Anymore questions ask away