Found this rather cool RC Lawn Mower, But no RC Tool Box...
Seriously though, you don't say what class you are racing, but My money would be on a Team Magic F8 Hauler Bag all day long... Or Similar (Venom etc) You'll be surprised how a few tools and a few sets of wheels & Tyres accumulate into taking pretty much everything you own - just in case!!! Keep your eye's open, someone must have one for sale..