Hi Mervyn,
Just read your post and thought I'd throw in my 'two penny worth' if it's any use to you.
A few years ago we owned a Carthago, which had a garage in the back. So, we bought a scooter and ran it up a ramp into the garage...very easy.
The motor-home we've got now is an Auto-Sleeper and I had a tow bar fitted together with a (motor) bike carrier by Watling Engineers. To be honest, it was excellent and reasonably priced (I carried a Yamaha on it). You just have to watch the wet weight of the bike and it's overall width. But that's individual to each van. It's a much cheaper option and easier to use as far as I was concerned.
On the positive side, it leaves you with a fully functional tow bar on your motor home. I've now got rid of the bike and got a Smart Car and trailer...so, it's a win/win situation as far as I'm concerned.
Good luck !
Eric