Most people use platform carriers for their added weight capacity. You have to have a trailer hitch installed on your vehicle.

The 1 1/4" hitch receivers that you can get for most cars are barely sufficient, as far as weight capacity, to hold two regular bikes. A 2" hitch receiver is better, and maybe you can get one for the Caravan.

Also, many platform carriers are only rated for two 35 pound bikes. You want to find one that's rated for two e-bikes, which are usually about 55 pounds with batteries. Owners remove the batteries to get the weight down.

My last big trip, the weight of the rack, two e-bikes, and my luggage sank the back of my car 2-3 inches. The bottom of the hitch scraped the ground when I went into gas stations or over buckled pavement. 2000 miles like that. Bummer.