>>1577439the wider 140 mm hubs were common on touring bikes and tandems at one point
to reduce the dish of the spokes and keep the wheel from bending sideways so much
smaller wheels or larger hub flanges will also have the same effect
one wheel trailers have a more simple mount but tend to be a little unstable, some are cheep but likely only just sufficient for your 20 kg ish cargo
most trailers do put a bit more stress on the rear wheel so its something to keep an eye on
rear wheels are the weak part of most bikes
