First, tie thin fishing line (that has enough tolerance for friction) to the landing gear of your bird, and fly over the tree, pull away horizontally, then return back nearer to tree, descend, so that the line pass over ”Y" shaped branch near the top of the tree. Then, tie thicker wire to the line, pull from opposite. Tie more thick wire to the 2nd wire and pull. Finally fix a light (maybe with support bar) and electric line to the 3rd wire, and pull. The 3rd wire could be left.
If the tree don't have "Y" shaped branch at the top, prepare "Y" shaped statue (or pulley), of which below part is reversed funnel, hung it with hook with "V" shaped line tied to both two P3 landing gears. Fly above the tree, aim with FPV camera full down, slowly down, and when the top of the tree is inserted into funnel, descend a bit to detach the hook from "V" shaped line, ascend P3P. Then do the above operation.
The problem is to fix the light (with bar) on the top of the tree - how about using "POI" operation? The 3rd wire above is tied parallel with thin line (with big friction this time), you tie the line to P3 landing gear softly, fly up, do "POI" action turning 20-30 rounds around the light and bar, then fly away from the tree so remove the line from gear.
Actually I don't believe this plan goes well, sorry.