Sorry, Erik...
No, it's not possible. Here's my way of putting it:
All nameplate addons have a dirty little secret; They don't create
nameplates. Every one of them just intercept the standard Blizz plates
and restyle them. We can't create, show, move, hide, or destroy
them. We can adjust their height and width, but only out-of-combat.
A nameplate that goes offscreen is hidden/destroyed by the Blizz
nameplate system. We have absolutely no control over this, nor can we
create and alter our own secure frames during combat.