. . . My next question is whether you think replacing the 1141 bulbs with the bulb-style LED would be best for this type of fixture or if the 36 flat in warm white would generate more light and be easier on the eye? . . .
I've tried both bulbs and the flat panels, and I'd definitely go with the flat panels. You loose a fair part of the light that bounces off the back reflector when you use a "bulb" shaped replacement. With the flat panels all the light is directed outward into your trailer.
I use the 48 LED "Warm White" flat panels from V-LEDS
. (Make sure you order the "Warm White" version, not the blue light "HID" ones.) They pull 2 watts (1156 bulbs use 18 watts) and are as bright or brighter than a conventional bulb.
I taped mine in using fiberglass tape. This works well, but I don't think it'll last. I'll use double-sided foam tape next time.