I ended up dolly-ing my Fiesta, because mine was a turbo model, which meant the baseplate install would have been more complicated due to the intercooler. But honestly can't even feel it's there, and behind my van, it netted nearly a 1MPG improvement! I like to think it's because the Fiesta fills in the low pressure area so well, but in reality its probably from driving more conservatively with car hooked up. I did not have a brake system, although I'm sure a heavy motorhome would probably benefit, if the brakes are already taxed.
I only got rid of it because I accidentally test drove a Focus ST. Don't do that if you don't want a new car;) And since my friend was also car shopping, the Fiesta had a good home to go to.
2000 Ford E450 V10 VAN! 450,000+ miles
2014 ORV really big trailer
2015 Ford Focus ST