Youíre trailer, I think, would look very attractive to potential purchasers. It looks in good shape, itís got a good colour combination and, absolutely best of all, itís clean.
When I bought my brand new trailer I did so because basically all the used ones were filthy that we could find ó that gave me the perception that the trailer overall was not cared for or well maintained. I couldnít believe people would try and sell a trailer looking like that🥺
With regard to your tack room, I think you might be better to strip everything out that was not factory original. I say this only because most horse folks have their own way of doing things and a blank canvas could be more enticing.
Good luck with both sale and purchase, evilamc.