Welcome to the forum Rob.
Why not take the bags with you when viewing a Zed for sale, then try to fit them in?
If people do the golfbag test, then I'm sure they'll agree to the two bags test...
Looking at the pics you posted Rob, they should fit. I'd put the longer bag behind the strut, and maybe the bigger back in front (although you might want to sort a way to secure the one in front of the strut). Or if by yourself in the car, on the floor in front of the passengers seat.
I've managed to fit in a fairly big suitcase in behind the strut, lowering it in with a blanket around to protect the plastic.
But as BM suggests take the bags along with you. Happy Zed hunting.