Because I started this thread I thought I might update everyone on the direction I finally took in my search for a personal mobility device to fit in the luggage compartment of my slider RV7A.
In reality there are so many variables and considerations between RV models that there is no one-size-fits-all solution.
I have a standard slider. A Meske tip-up slider, or a Supa Track modification will provide more options due to better access to the baggage compartment but the standard slider provides virtually no realistic options for putting your local transportation fully in the baggage area.
In the end I opted to purchase an E-Glide G120 electric scooter (sold in the US as a Levy Plus). The stem folds but even so it will not fit entirely in the baggage compartment (too long) even on the diagonal. I accomodate it by detaching the rear of the passenger seat and placing the scooter in the plane longitudinally with the front wheel resting on the base of the passenger seat. It is then held in place with the passenger seat harness. The advantage of this arrangement is that the scooter, which only weighs 11kg, is very easy to lift in and out of the aircraft.
The scooter is very robust (I've already done 1000 km on it now and no problems) and will comfortably do 30 kph on a flat surface. It's good for about 40km on a full battery. It's a great device for getting from airfields into regional towns. You can buy escooters that fold up into smaller spaces and one of them might fully fit in the baggage compartment of a slider....but the escooters that fold multiple times into a small space are invariably flimsy machines.
The downside of my arrangement is that I cannot take a passenger and the scooter at the same time. But for cross country travelling on my own it's just great.
So, here it is.