I think everybody that has never done this needs to step back and take a breath!
Around many boat yards, the "Pyramid" method is common if not the preferred method of moving
boats on
shipping cradles. Around Atlanta, several dealers and haulers moved dozens of sailboats every year ranging from around 5000-20000 lbs the same way, to and from our lots to the local lakes, in and out of indoor boat shows, and sometimes even
ramp launched them. Over a 20 year period, I don't
recall any issues.
With some sense and experience, I think we all considered it to be the safest way, while cranes, forklifts and even travel lifts had accidents.
Of note- we used a pair welded
steel pipe "saw horses" for the "front" of the load for support as they were much more stable if tapped with the trailer, and we used a 12' wide flange steel beam for lifting since it was more stable on the flats. The horses had a steel peg on each end to keep the beam from slipping off. I don't like your wooden beam very well, it can turn on it's side too easily. We tightly chained the beam to the
cradle. You have to know where your CG is and make sure it lands properly on the trailer and never get one end too high in relation to the other, even it it requires multiple lifts.
Your
equipment needs to be in perfect condition- no old chain, stands or jacks and with plenty of
safety margin. Your 2x4 stands look a little shaky to me!
When anything fails during a
lift, it is not usually slowly- more like an explosion!! Keep all body
parts and people out of the way! There is no way to move clear fast enough if it starts to come down!
We often towed with a similar sized rig, on a reasonably flat tow, the truck makes less difference than using a trailer strong enough (oversize?) that it won't flex very much, and with good well balanced working brakes. I don't trust anything but chain and proper
commercial chain tensioners to tie the cradle to the trailer.
Be careful!
Bruce