If you are happy with the placement and style of the existing light
fixtures that you have, then replace the bulbs as you have been considering. But adding LED lights
to your interior is the perfect time to put fixtures where you really
need them. In our 13' 1984 Burro
, we added LED fixtures to illuminate the front dinette area (formerly a bunk) and the rear bed area. The small puck fixtures are relatively inexpensive and can be put on dimmers. If you are handy you can figure out how to run the small 12V wires to where you need them.
We also put a flexible light
strip composed of a line of LED's over the sink-stove area, also on a dimmer. This was a terrific upgrade from the stock light which was a fluorescent tube shining in your face. The strips can be cut at about every 2 inches allowing you to make exact custom lengths. If you are cheap like me you also don't need the special clip on connectors. Just solder on 18 ga wires with a $4 Radio Shack soldering iron.
Parts came from:
If you use dimmers be sure to get PWM style (pulse width modulation) as standard dimmers for incandescent will not work. But don't get the cheap $5 dimmers from china. They will not handle the vibration in a trailer and may fail.
Most folks agree that you should get warm white LED's and not "white" as the plain white are too blue and not pleasing.
As for replacing the lamps in the existing fixtures, you get more bang for the buck by changing the cheap socket fixture in your light for a bayonette style mount which will enable you to use the flat cluster lamp style which typically are brighter behind the diffuser in your fixture.