Yes we'll want the small dog in the smallest crate possible that is still comfortable for her. The ideal crate is the kind that comes apart in two pieces or collapses for storage. The door openings are not large so it's necessary to put through the door in pieces or collapsed then assemble inside. There is a baggage area behind the back seat dimensions approximately 25 x 30 inches where we'll load the smaller dog. I know that's pretty cozy so if it sounds too small let me know. The great dane can have both back seats to him/her self (back seat area 36 inches wide). I have a harness that fits my 100 lb Labrador we can use with a leash to keep secure.