I've seen new cab/chassis trucks with a new custom haulers bed/feed bed/work bed types with LED stop/turn at the normal location at the bottom/rear of the bed and another set at the top at each corner of the headache rack. Damz things were too bright.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides
Well I have never been to Spokane so I haven't seen your trailer . I suppose others have added one also . Do you know of any manufacturer that has installed one . I don't know of the legality one way or the other .