There is not much difference in a base 2003 TrailLite vs fully optioned to make a significant difference in market value at ten years or older. If you are trying to check off boxes on a NADA or Kelly web oage, there is no consistency in how the information is used, most of what is on the list of options was standard equipment.
Fair value of a RV that old depends a lot more on current condition, than whether the air conditioner was standard equipment or part of a mandatory "option package" at time of original sale. I used to have TraiLite brochures from 2004-2006 but tossed them a few years ago when the parent company folded.
No web site to get the information. TrailLite should be able to get a build sheet from the final vehicle VIN (not the chassis VIN) if those records were not "lost" with the Monaco Corp bankruptcy.