you may have the room but what are you going attach your tie down straps to , not much in a mini van as far as true hard points to tie down to .
If you tie down and ratchet to much to keep the bike from moving you could rip through the thin sheet metal in the floor or sides, vans are not trucks , just like cars are not made to pull stuff. although you may acomplish getting it in the van , It would really suck if the bike you just bought falls over , and breaks several things on the bike or breaks out your vans windows because it was to much for thin sheet metal, and NO the child tether points are not strong enough either to hold 500 pounds from faling over , and ripping them out of the floor , your wife would be really pissed at you for that,
Please rent a truck you can get one for less than $100 for a day. cheaper than fixing the bike and your minivavn. or better yet find some one with a truck and borrow it or give them $50 bucks for it for a day, Hell I'd pick it up for you if you lived close , but you probably dont. any ways Good luck and welcome the BUELL FAMILY, and RIDE SAFE.