I think there's a creative option likely available, but it's too damn cold right now for me to mock something up in the garage. I might try order a few inexpensive gas strut options from amazon in the spring and see if I can make something work
Something like this attached to the top of the bumper and the inside part of the swingarm might work so long as there's clearance between the swingout arm and the lower tailgate when everything is closed. However clearance might be tight as you wouldn't want the tailgate to contact the top of the strut when it's lowered
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Anyway it's essentially what the Slee design uses, I'm just imagining the end that connects to the arm to be rotated 90* and mounted into/through the arm rather than to a plate welded to the bottom like their design uses.