I modified our ancient 6’ x 4’ ‘box’ trailer to carry our two Old Town Pack Angler canoes and my 225 cc Yamaha Serow motorcycle. I achieved this with three simple ‘drop-in’ welded steel sections which come out/in in a minute when you need the trailer for something else – such as transporting sheep. It may not be apparent that I have welded four pieces of box section to the corners of the trailer so that the two end steel pieces simply slide in (and hold down the motorcycle track). It is a simple and effective arrangement.
I can tie the second canoe right side up on top of the first one (shown). This arrangement proved perfectly sound even on rough 4WD tracks such as we often frequent. It gives us single car access to sections of river which we want to canoe together. I realise some aspects of it could be done much better (and the whole arrangement could be finished – and painted), but I don’t need to ‘get a life’. I already have one!
It was all done somewhat hastily so we could complete our Wonnangatta canoe trip – whilst there was water. See eg: http://www.theultralighthiker.com/wonnangatta-waterford-to-angusvale-day-one/