Hi Colin,
The dimensions of Peter's trolley system are as follows . . .
With the handle "closed" it's roughly 30"long x18"wide x28"high and the containers are 11"x10"x19"high but two together are only 37" because the handle goes into a recess in the bottom of the next drum. Remember the hose reels have to go somewhere and the poles will go on the roofrack.
Hope this helps a bit.
PS
My usual call to first time posters - Tell us a bit more about yourself, fill in the profile, personal text and signature. As you say, you'll learn so much from these boards - ENJOY!
PPS
Consider saving for a van, after a while you'll get totally hacked off having to take the gear out and in to let passengers travel with you.