The only issue you have to worry about with 1.25" to 2" adapters is long is it and how far the rack+ebikds will stick out away from the bumper. That will reduce the tongue weight you can have hanging off the rear if the extension is too long. Too much weight on the rear can droop the rear too much and raise the front end (headlights too high and might blind on coming traffic and possible reduced handling/steering/braking feel).
Usually; but, not always, tongue weight limits is about 10% of the towing capacity. Having almost +120-150 lbs of ebikes PLUS the weight of the bike rack might already be at the limits or exceeds your tongue weight for the hybrid? It might be an option to hang the rover off the rear on a rack and put the folded mini in the rear seat?
I'm pushing the limits with my two rovers+rack that comes in at 200 lbs for my smaller SUV with 1500lbs tow rating (150lbs tongue weight). I switch to my larger SUV with 500lbs tongue weight if I have to add a 3rd or 4th bike to the rack.