I think it is just a matter of cinching the whoopie after placing it above the Marlinspike hitch. You have to compress the Marlinspike hitch, or the whoopie can slide over it, twisting the toggle on the way. I like to tighten the hitch by pulling on the bitter end of the tree hugger before placing the whoopie over the hitch.
HB, what you describe is similar... you are cinching the Marlinspike hitch by burying the whoopie into it. You can do exactly the same thing with the whoopie above the hitch. The point is, make sure the Marlinspike hitch is well compressed and tightened before you move on.
To make the whoopie attachment above the Marlinspike hitch an offshore rig, one would seize the whoopie so that the eye is closed around the hugger. Not practical in this application.