DO NOT fasten tightly! DO support tailboom!
RHC doesn't want us to trailer their helicopters, because they don't want to have to field all the resulting questions. "We designed it to fly, not to be trailered."
But they do say LET THE SKIDS FLEX sidewards, for that is the natural suspension of the helicopter, bolting skids down tight will result in fatigue cracks in gear mount knuckles. So mine is chain-tethered at the 4 corners of skids, to the trailer, free to dance around but not slide off (it never even tries to slide off).
They do say SUPPORT THE TAIL BOOM very carefully or you will get cracks in the upper frame where it attaches. I use a steel gallows, cloth sling, and multiple preloaded bungees (my guess is that the tailboom weighs 50#, the factory doesn't know!!!)
They do say SUPPORT THE MAIN ROTOR BLADES about 5' in from the tips. This is to protect the droop stops AND to minimize flexing/folding of blades. I use 5'-long cuffs supported by flexible cords on a rigid trampoline supported by steel-tube A-frames to the trailer frame.
And they will not reveal even a single instance of a Robinson having been damaged in any way by being trailered. Doesn't mean it hasn't happened; but it suggests trailering is not especially dangerous.
There seem to be many (50?) R22's on trailers on USA highways. Opinions on trailer design run the full gamut, I have yet to discover an engineering analysis for the ideal trailer.
My own, in use 2 years/30,000 miles without incident, is an open single-axle 2000# GW converted snowmobile trailer, intended (by me) for smooth highway travel only. 2-axle trailers are common, usually 7500# GW. RHC and others recommend making sure the trailer is loaded to max weight so the springs will act as softly as possible--I don't know how to do that with two or three axles, for they don't make (or I haven't seen) low-capacity axle-spring combos facilitating loading to max gross weight with only a 1000# helicopter! (Enclosing the trailer would go a long way in that direction.)
I have a flat bed. Training/safety wings fold out flat for TO/Ldg making the trailer 12' wide. After two years of this, I begin to think I would better have had wide 15" high skid-guiding-channels at sides of trailer, so that once you position skids in hover & descend vertically the channels guide the chopper straight down, and you can be more assured that chopping the collective at any lateral lurch wll result in aborting dynamic rollover safely. Other trailers seem to be evenly divided between methods.
How steady are your nerves? Tooling down the highway/track with all those potholes/pseudo-drivers trying to nail you and your helicopter will give you ulcers in short order! AND there's no hard-core engineering data to tell you you're not accumulating fatigue cycles in the worst possible unsuspected places, your heirs will be the first to hear the post-mortem analysis. Very scary.
Dave