My plan for these cars (I have ten cars each of the R32 and R40 sets) was to power each strip directly from the regulator board, and pin the strips between the ceiling panel and roof (after insulating the metal strips). Only thing I would have to remove is the original bulbs. To bridge the gaps between light-bulb openings, I'd space out each three-LED section with jumper wires. Makes it easy to solder them together on a bench and then place them face-down on the OEM ceiling rack.
---PCJ