Hi - I had exactly the same question two years ago when I was shopping for Rv-8s. I never found the exact answer, and when I saw this question pop up, I told myself I would measure and answer it. But, I kept forgetting until last week.
Anyway, I've measured my baggage area and attached an annotated version of the schematic that Van's has on their site.
In short, the entry way into the baggage area is 27.75 inches tall, and 21.5 inches wide at the bulkhead. There's a little more width right behind the bulkhead, but e-bikes and scooters are a tight fit.
There is a structural member from 19.5 - 20.1 inches above the floor that protrudes in, and reduces width at that location to 19.75 inches.
I got a used Brompton folding e-bike that folds down to about 25.3' H' x 23'' W x 10.6'' D. It DOES just barely fit in there, I have to wedge it in at an angle. Its actually easier to take out the back seat, toss in the bike, and then reinstall the back seat, than try to angle it in perfectly in 3 dimensions while fighting with the seat back.
Plenty of room *behind* the bike for clothes and helmets and things, whatever will fit on that back shelf.
Also, bear in mind that the back seat protrudes about 2 inches into the compartment.
If you want photos of the actual measurements, I can send via PM.