I'd strongly recommend a roof rack to carry your kayak, vs leaving the tailgate open.
I've got the Thule rack and J-brackets on my Jeep.
Yep, its a bit off a hoist to get the 49 pound kayaks up there. So, I've fabricated a simple guide bracket assy to lighten the task. I can easily get the kayaks on and off in a matter of a minute or two - by myself. My wife is just too short to be of any assistance here.
1. I strapped a 1.5 in PVC pipe just under the front edge of the roof rack. To minimize the appearance of the white pipe on the Jeep, I Plasti-dipped the PVC.
2. I found a short section of pipe that exactly fits INSIDE the PVC pipe (2-3 ft long), and added an "L" shaped section in PVC. I drilled thru the PVC and inside pipe and added a bail clip to secure.
3. $10 - $15 at Home Depot for the pieces.
This is what it looks like:
The load/unload process is simple (only need to lift 1/2 the weight at a time - 25 lbs is much easier than 49 lbs over head!).
1. Lift just the nose of the kayak up onto the guide bracket (tail remains on the ground)
2. Lift the tail of the kayak and push the the boat forward over the guide bracket into position
3. From a small step ladder, push the kayak up onto the J-Bracket and strap into place. The step ladder REALLY helps eliminate much of the reaching and stretching needed to get the kayaks up there.
4. I drape a rubber backed carpet between the roof rack, down over the door/window to protect the PAINT from any touches from the kayak on the way up or down (yep, I have a few nice scratches in the clearcoat BEFORE I added the carpet!)
5. Remove the guide bracket and attach on the opposite side and repeat!
6. Remove the bracket when not in use - the black PVC mostly disappears.
Really could not be much easier than this!