I changed to LED bulbs in our 2005 Crusader. I used G4 2W COB led's for the spots.
For the larger oval lights, I used some 12W led strip like this - https://www.amazon.co.uk/gp/product/B00JQV6SFU. I soldered 3 short lengths (that would fit in the light) together for each light and you also have to remove the ballast thing. It was a bit fiddly and the soldering took a bit of time but it worked in the end... I would get non-waterproof led strip as the waterproofing is a pain to get off for the soldering.
There was a video/webpage showing how to do this but I can't find it.