A new unit came for me today in the post. It's made up of the character minifigs from the Adventurers sets:
Plus that big vehicle base plate I mentioned ordering some time back:
I am still searching for suitable wheels to use on it, with a probable maximum diameter of 54mm.
Also, I was stupid enough to go looking for suitable wheels on EvilBay and wound up ordering a set of 4 Lego trikes, two white two black, for £10. Complete trikes with wheels and everything, so not bad for that price. Looks like I am going to make a 5 vehicle unit soon with those four trikes and the motorcycle dude from Pharaoh's Quest. WOOT.
Still have not found the wheels I want, though...