I'm not sure how practical it is (or if anything like it has been suggested), but it seems to me that the main issue here is the search algorithm for "nearest item" more than the actual pathfinding to the object. It would make sense to improve that first, instead of using the existing "find nearest in terms of sheer physical distance" algorithm. What I came up with for that is a sort of radial trailer pathfinding algorithm. It's directly fractal at the moment and could use some refinement as a result, but I think it's on the right track.
Basically, it works something like this: for east, north, west, south, up, and down, perform an expanding cone of searches out 1 tile "forward", "up-forward", "down-forward", above, and below (for cardinal directions; up/down it'd get a lot messier since you'd have to do a genuine 9-tile radial search). If an acceptable item is found (or the trailer in that direction is impassible), its location and distance are noted (if there was an item; otherwise, it returns null) and that trailer of the search is cut off. Repeat until all trailers either locate something or null out, then do a comparison to find the genuinely closest object. This would lead to a LOT of trailers, and some noticeable search overlap, but it would also have very thorough coverage. Its main issue (besides the massive number of small checks) would be very odd layouts with lots of corners.