Pruning it back some might be a good idea since the root ball has been cut back from digging up. With a smaller root ball it will be harder for the plant to supply food to a 7 ft tall rose anyway.

Dig your hole and get it in place and keep it very well watered but no fertilizer until you start to see new growth on it. You might want to find a way to shade it some during the hottest part of the day for a while too. It will probably suffer some wilt and shock but it should be OK with time.

A rose 7' tall will fit lying on its side. The cargo bed of my old Suburban is 4x8', with another 2' of narrow width going forward across the dashboard. Often transport plants that way. Confine the soil in the pot by slipping it into a shopping or trash bag & tying or taping it closed. If you can cinch in the branches, it will be easier to handle & protect them. This can be done with twine, an old sheet torn into long pieces, burlap, bubblewrap, trashbags cut down the sides, landcape fabric, household plastic wrap - whatever you have on hand that can be used to wrap the branches & be tied or taped closed. Think of the way Christmas trees' branches are tied when shipped to get a picture. Or you can stand the pot in the middle of an old sheet & pull opposite corners of the sheet to the top of the plant, tie or clip & repeat on the next set of corners. You can bundle with twine or masking tape or bungee cords or whatever over the sheet. You don't need to do this, but it helps limit any breakage by compacting a plant this way. You can use a box instead if you have one the right size to accomplish the same thing. You may have to slit the box down two or four sides to put in the plant, brace the pot itself in the bottom & tape the sides closed. Newspaper wadded around the plant in the box can help pad the branches.

If you've bundled the plant, it will be easier to load into the vehicle. (Plan on wearing a long-sleeved shirt & gloves for moving any rose!) Position the plant far enough away from the entry so when you tilt the plant it's top is aligned to go in. Towels or quilts or some type of padding will be useful bunched up across the width of the cargo space where you anticipate the top will rest once loaded. Usually load the top of the plant first so the pot is against the back doors, as it can take two people to load it pot-first & remove again. Stand sideways to the entry, tilt the pot toward your destination, grab hold of it with one hand cradling it on the side & the other on the bottom.Or you can hug the pot to lift it, bracing it against your torso. Lift & guide it into the cargo. A large piece of cardboard on the floor will help it slide forward. An open box around the pot once it's in will keep it from rolling, or anything else to brace it.

Sounds harder than it is! Tall plants at nurseries usually only get the sheet wrap & a box for the pot. (Okay, admit I carry this stuff & more in the back all the time. Never know what I'll chance upon that wants to come home with me.) Go get your (My) Girl!

Seril thanks for the advice! And Vasue thanks for ideas on how to get it in back of the SUV, sounds like you might has done this a few times :). I should be getting it this weekend and will get it in the ground as soon as possible and keep my fingers crossed it makes it! I'm a little nervous because she has it in a pot for the last few weeks and I'm not sure of its condition. Is My Girl a bushy rose bush?

Unfamiliar with My Girl - helpmefind turns up 4 - which do you suppose it is? (Yes, quite a few times, hardcore.)

Here is a link that might be useful: My Girl