I don't tend to work on my RB "on site", I like doing it when I'm out the way, somewhere stable and won't get "what does that do?" or "why don't you do it this way?". Possibly one of those red lights you get outside darkrooms with a sign saying "if the light is on then shut the f**k up and don't speak to me"
If my RB packs in before a dive then I usually sit it out rather than rushing to fix something badly just to catch a dive.
I'm happy with just somewhere flat, maybe with some bowls formed/fixed in it for chucking screws, etc. A big, feck off catering pack of kitchen roll would be handy but I wouldn't bother will tools or spares, they'll either get nicked or divers will complain that you don't have a [insert item here]. I've got a toolbox that has just about everything in it I need to keep my RB going and I can distill that into a little tool bag for taking on boats. Somewhere safe/dry to stash a toolbox would be handy. Don't keep spare cells, there's no point, they age and they need to wake up before it can be used anyway. I imagine there would be a big liability issue as well. Diving on just two cells is a good skill to practice anyway... Batteries, I can still dive mine manually even with a failed battery so I'm alright 
For filling the scrubber, I'd definitely get some sort of slop tray rigged. I prop the can on a couple of bricks inside a rubble sack. Deck level is best, as others have said lifting a full lime keg and aiming it is a pain. A couple of funnels handy would be good, but again they'll probably get nicked.
I agree with Zak, a couple of wine boxes nearby is helpful. A stack of porn would be nice as well.
Cheers,
Stuart
Last edited by NotDeadYet; 05-01-09 at 09:59 AM.
"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me" Hunter S Thompson