Take no notice of that loon from Normandy (Raynipper) Debs! Ill have him know my late night music videos are a YouTube sensation!
Welcome by the way.
On a serious (ish) note I'm glad that Geoff mentioned payload as if your scooter is 105kg that's pretty much the same weight as a lightweight 100 or 125 two wheeled scooter.
There are loads of threads about fitting them or carrying them on motorhomes and a hell of a lot of vans just do not have the available free payload weight to take one. You will face this same issue so you may find the ideal van but It may not be up to the job of carrying the scooter.
The other thing to watch out for is manufacturers and dealers claims of what the payload "should" be. Never take their word for it. The only true way to calculate it is to take the prospective van to a weigh bridge and weigh the whole van with you both in it and then the front and rear axle independently.
Any dealer worth his salt or private seller should let you do this and there are plenty of weigh stations all over.
There is a handy calculator on the web and I think on here but I can't direct you to it right now as I'm on my mobile sunbathing (at last) by the van.
A rack on the back for the scooter or even a small trailer would allow you freedom of layout inside but the further back the weight from the rear axle the more it adds to the weight on the back axle. A garaged scooter means a raised rear bed.
Another option could be a lightweight Motorhome scooter or electric chair for the van and leave the heavy one at home. I know nothing about them but presumably you do.
There was a bloke here the other day that had a small one on a rack behind his van.
As for worrying about the size. Al will be chucking it around in no time like the proverbial white van man!
Ours is 7.5 metres and gets chucked around mountain roads and all sorts on single tracks. Anyway you only need to look out the front and the rest will follow.
If you fit a solid chassis mounted rack on the back like we have they are great for punting out of the way wheelie bins, lamp posts and Frenchmen.