Just be aware the LED lights require a whole different kind of dimmer than the 12V Incandescent automotive bulbs do. Automotive dimmers can use a variable 12VDC source where the LED DIMMERS require a PULSE WIDTH source of 12VDC or something to that effect. LED dimmers are not expensive however - check AMAZON with LED LIGHT DIMMER in search on GOOGLE followed by the word AMAZON... Should not be too hard to find both polarities on the fixtures... Has to have both + and - DC levels to work...
RV Color code is WHITE for frame ground (-12VDC) and any colored wire including white with a color stripe on it for +12VDC.
Roy ken