Thanks for all the replies so far.
It looks that C is quite popular here and it does look like the most universal cart. I'm leaning towards a hybrid of A & B with a bit of C thrown in.
Out of the material I have I think I could make a cart that will look like A with the bend in the rear like B (I think a bit of a ramp might come in handy). If I cut the 2 180 degree into 4 90's, I can use 2 90's in the front of the cart for a nice kick up to mount a handle and winch.
I would like to have the whole cart and ski to slide onto my trailer with the cart becoming the trailer bunks.
The trailers winch would be used to pull the whole deal onto the trailer.
Might be cool to pull up to the local riding spot, pull the cart and ski off of the trailer and head to the water. After a nice day of riding pull the ski onto the cart and than winch the cart and ski onto the trailer back at the parking lot............or not.
Picked up the rolling stock today (2 wheels, 1 axle and some pins) for $70 bringing the total investment to $90.