I know this is an old thread, but back in '02, I was at the factroy in Butler, OH., (just before they moved), checking out their trailers, and the gentleman showing me around said that they were building four 34 foot trailers as a special order. Said the extra 3 feet went into the bedroom layout. Offered to build me one too while they were at it, if I wanted.
I don't know what the longest trailer H-Lo ever built was, but I pretty sure they built some 34 footers.