I'm hoping you come back to this thread to post your results.
I think my biggest concern wouldn't be whether you use 4L or 4H (you can probably experiment with that choice on the first climb where you could back down a short distance if you found your choice was incorrect) but hanging the trailer up on the hill transitions. Another concern is the hitch PIN coming in contact with your tailgate if, again, the transitions from down to up are too great.
One thing for sure is that you won't know until you get there with the trailer hooked up and see the geometry of the whole thing.
Please come back and let us know how it goes. Pictures would be great.