The RV comes back home

Today we went back to Telford to collect the RV after it had had the outstanding jobs done on it. It was lovely to see it again - and made me wish we were off on our travels again immediately instead of (hopefully) in late September. Yes, gluttons for punishment, but as Keith said, we can't let the ******* who robbed us get the better of us. I suppose it's a bit like getting back on a horse or a bike after falling off and anyway, we need a fact-finding tour to check out where we want to live when the time comes.
The RV lives at Keith's Dad's house, which is at present being done up, and it is a very snug fit, so the usual practice is to ask Giles to pop over and shout out the relevant instructions for guiding it into the garden. Today however, he was unobtainable, which meant that the whole responsibility fell on the shoulders of yours truly. Two problems:
1. Keith can't hear me when I shout instructions from the rear of the vehicle.
2. I'm not sure what instructions to shout.
I know what I want him to do, but I don't know how to tell him how to do it. For instance, 'left hand down a bit' - does that mean that the wheels will turn left or right and consequently, will the van go left or right? 'Full lock' - well what on earth does that mean?
We managed to get it in without too much trouble but I need to have a set of meaningful instructions to shout out - oh and a megaphone to do it with.