Re: loading pontoon on scissors trailer
I have a 25'er that I use a scissor lift trailer for. Here is what I do. I back the trailer into the water and lower the scissor deck down to the point that the front stops are a little higher (6 insches or so ) than the bottom of the front deck of the pontoon. I then have someone drive the pontoon (slowly) onto the trailer applying power until the front hits the stops.
The person on the boat keeps the engine in forward to keep the boat up against the stops while I crank up the scissor deck. The engine can be used to adjust the backend because it will swing around while floating. Once the trailer has a good part of the boat up, I shutdown and raise the outboard. I finish raising the deck of the trailer and set the pin.
I attach a strap between each pontoon and the winch post on the trailer and tighten.. This will keep it from slipping back when you pull out. Before pulling the boat out of the water I look down underneath the pontoon to ensure the trailer is lined up correctly.
The pieces you will need to figure out is how deep the trailer is backed in (trial and error - but tires fully submerged is a good start) and how you line it up and keep it lined up while cranking the trailer. I told you my method, but I have a good feel for it from practice.
With a 20ft yours will be a bit easier. When I owned a 21ft'er I had a long stick that I would use of the back to ensure my trailer was lined up as the boat was pulled out.
All in all, it only takes me and an unskilled friend a few minutes to get it lined up and up the ramp.