If the pancake style of light fixtures, another option would be to replaced the existing lights with some that come with LEDS in them (that aren't a conversion). Available on ebay for around $15 and up.
Our 2014 TT came with pancake lights in them with OEM LEDs in them. I removed them all and replaced them with the light fixtures shown below from Kaper II. They have roughly the same footprint as the original lights and cover the existing screw holes. They're only about 1/2" thick.
I would get warm white lamps. The interior of RVs these days is typically warm colors (cabinets, flooring, upholstery, etc.) and warm color lamps will look and "feel" better for that reason alone. Cool color lamps will clash and seem unnatural and harsh. There's some that prefer cool over warm though and won't do without it.
I prefer the overhead lighting in our living/kitchen area to be on the brighter side for task lighting and cleaning. On 3 sides, we have puck lights under cabinets & slides and when watching TV, just have one set of the puck lights on. Our bedroom only had one pancake light and it was way too dim so I added a 2nd light (as in pic). I also added a puck light in the shower because that was dim too. Lighting levels are just a matter of personal preference. I also installed a couple of the removed LED pancake lights in our pass-through which works great when it's dark out.
If cost is an issue, LED replacements is the way to go and they are very inexpensive these days (on ebay at least).