I just wanted to share something that I prototyped for my EP and have done another iteration for my PM.  It's a very simple beach/ramp launch dolly for when you can't just back down into the water with the trailer.

Other than the three 2x4's, it uses a couple of wheelbarrow wheels from harbor freight and some 5/8" x 7" galvanized bolts, nuts and washers, some glue and some screws.

The theory was a stable dolly that could "lock" into the skids that could be trundled across some pretty rough ground.  It also fits snugly between the thwarts in the back of the PM, so it's very road-friendly.

For my PM, here's the cutlist from the 2x4's:

1)  2 x 42" = Bunks

2)  2 x 26" = Supports

3)  2 x 25-1/2" = Cross Braces

4)  2 x 23-1/2" = Leaf Springs

5)  2 x 10" = Axle Housing

The woodworking is just cutting all the parts to length, rounding over or easing the edges to make it more boat friendly.  I paid special attention to where the parts snug up against the thwarts and I made a matching radius on the insides of the bunks that match the radius of the fillets on my skids.

Here are some pics.  Let me know if you have any questions, need additional info/dimensions, etc.

Here's a pic of the assembly upside down showing the structure and how it locks into the skids.

Here's a pic showing the wheels installed.  I deliberately placed the wheels off-center in order for it to stay tipped so it's easier to slide the boat up on it.

Here's a pic showing the final assembly upside down.  With this version, I think there's actually enough clearance between the tire and the hull that I could actually eliminate one whole 2x4 layer, which would make it lighter and lower.  Since I only need three 2x4, it will be easy to knock out another version.

In use, I just line the dolly up with the pivot point of the skeg, off to the side.  Then I pick up the bow, pivot the whole boat until the skids are lined up with the dolly, then lower it down.  I make any small adjustments to get the skids to drop into place, then I move the dolly fore and aft to find the balance point of the boat.  Then I'm off.  I've actually used this arrangement to haul the boat 100 yards from the parking lot to the ramp.