Long and short of it is not to unless you have to.
If you do, then from what I've seen in the game industry in South Africa, you need two axles and pay special attention to the way the blade is secured. If not, they tend to break where they've been held, especially if you go off tar roads.
Putting a fuel tank under the chassis is a nice addition if money and regulations permit (your fuel company will advise on legalities of this). This also keeps the C of G low and gives you options beyond fuel drums on the back of whatever you are towing with.
Try Bassair Aviation in Pretoria, South Africa on +27 12 543 3303 as they have a lot of experience in trailering R22s.
Just make sure what your insurance company has to say. Two machines were lost this year flying off the trailer...