Thanks for the tips, guys. The bikes are a KTM 525 and a KLR 650. With the custom windscreens, it would be tough to shoehorn them into a minivan.
I'll try swinging by some of my local rental companies and seeing if they're more reasonable in person. I hadn't tried Penske yet, thanks for the tip!$400 is about all I'd want to spend, or else I'd be better off paying one of my buddies to drive my truck.