Robert,
Our M101's tongue has a 20 lb cylinder's footprint well inside the angles of the drawbar. I can imagine off-road situations where the space the cylinder sits in might be intruded by the tow vehicle.
This interference problem would come to the fore if there was a rear-mounted spare on the tow vehicle. Definitely wouldn't work there.
A new bumper and spare tire carrier are a long term plan for our Land Cruiser, but if and when it happens it will be after the trailer's tongue modifications.
The box I'm considering in lieu of finding something better will protect the cylinder so that it would take the brunt of any interference.
I don't expect to operate the trailer on any extreme trails, which is the only time where such a problematic angle could become a factor. I doubt I'd want to take an 80 series on such a trail, but I'm only hardcore if I get into something I wasn't expecting.
I'm not saying a different solution works for people. These cylinders are meant to be portable and depending on the situation, I see nothing wrong with strapping a cylinder inside an open trailer. I'm just surprised that a simple and secure option is so hard to find.
Lucky,
Not expecting to get hassled, everyone's real friendly in Canada. I just want it tied down so it doesn't worry me as maybe bouncing around through the back window in an accident. It's not the cops that worry me, it's those darn moose, etc wandering around on the roads:bike_rider: