Bonding two males can be difficult, but I think you are doing the right thing by making a good try at it before considering your other options.
As far as the car ride, there are several ways that people do this. With two bunnies that have been fighting, this is what I would recommend. I would recommend finding a friend to help you, then bringing the two buns to the car separately, one in a large box or laundry basket, and the other in a carrier. Then, you sit in the back with your bunnies while your friend drives. While your friend is driving, put the other bunny into the laundry basket, and hopefully they will be so nervous that they will not fight but just snuggle together. Then, once you’ve driven around for about 15 minutes, you can bring them both back into the house and put them into a neutral bonding space. The stress from the car ride will also help them be more calm for the bonding session.
Also, just as a side note, the size of the bunny does not determine who will get the worst of the fighting. My little netherland dwarf kicked my larger English Spot bunny’s butt once! (I wasn’t home and somehow the netherland dwarf got out of his cage and into the other cage).