This is neat.
I JUST JUST did this exact thing on my 2615HST.,...for a snowblower.
Change your post title to "Installing rear lights on 2615" & I'll post up my pictures & how I did it.
I can't get my pics off my camera for some reason.
I came to the conclusion that to do it right I'd have to run a totally separate wire (+12V) back to the ROPS from the key switch. Then rather than put an in-line fuse in some wierd lame location I decided to try to use the factory fuse panel. THEN since I knew I'd be adding more electrical circits in the future I decided to just get it over with and run the wires, put in the fuses, etc. right now.
So,...I bought a few 4-flat trailer wiring connections, some wire flex loom, heat shirnk solderless elect connections, a aux fuse panel (to steal the fuse holders out of), etc.
I jumpered from the wire that gets 12V when the key is turned on to three other fuse holders. From the other side of the fuses I tired in three wires from the 4-flat wiring & left one spare just in fuse panel area capped. I ran from there up into the dash where I installed two waterproof toogle switches. One switch is for the rear lights & one is for emergency/plowing lights (not yet installed)
From there I went out under the tractor right beside the factory wiring bundle with my bundle of four wires (yellow, brown, blue, & white) back the a Y then to each ROPS attachment point. There I put on individual plug-in conectors for each wire. Then I ran up the ROPS to my rear lights.
I have a four flat plug connector everywhere factory wiring had a plug connector.
I ran a ground wire from the chasis under the dash to every load/ future load.
I relabled the fuse panel cover to match the loads being fed.
I encased everything is 3/8" or 1/2" black flex loom
I taped red tape around the flex loom every 6" to identify it from the stock wiring.
I left two spare wires from the fuse panel in the dash for future use.
I left two spare wires from the rear area of the tractor in the dash for future use.
I found out that there already is a spare wire & fuse holder in the fuse panel but the wire gauge is small & it ends in the dash.
It all took me longer than I though it would,...about 6 hours.
It came out nice though & for the next three electrical loads I add to the tractor it will be easy.