Sometimes the seat mounting hardware is so rusted that the studs snap off. Thus another repair needed. All of these service procedures are in factory service manuals. None of them state "remove front seat".
There isn't a major mod required to replace the 4 incandescent bulbs for illumination with LEDs. The correct LED bulb fits the same original sockets. They will be brighter than OEM and live many years longer. Good luck with it.