In 2009 at the Penrith Ulysses AGM I purchased a camper trailer very similar to Blackduck's project, and towed it behind a Honda 900 Hornet with very little trouble either uphill or down.
The trailer was all steel with a solid axle with leaf springs, and measured 5' X 3' X 1'. The tailgate swung outwards and was wide enough for me to mount a 2 burner gas stove.
All up it weighed 153 kg, with 15 kg on the ball.
The only disadvantage was the lack of a dressing room as you can see in the photos.
I had mounted a teensy gas bottle behind the left mudguard, with two 5 litre water bottles in front on both sides. I even went so far as to get a 30cm port-a-potty which
just fitted.
I also had an Esky mounted on the front between the tow ball and trailer. In the following photo, you can just make out the mount:
The whole setup also included a flat canvas awning as you can see in the next pic:
There is one quite similar on eBay:
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=251592837394