Here's my solution to shallow ramps. Would have opted for a tongue extension, but the angle iron under the tongue that the chain connects to was in the way and several other factors made it impossible to do. This hitch extension is made from a section of 7'9" 2" x 1/4" steel tubing. The steel and the welding of the ball plate was $65. As you can see, it almost touches the ground when loaded.
I decided to install a wheel on the tongue end of it.This wheel was on sale at harbor freight from $19 online to $10 at my local store. It is a 10" pnuematic swivel castor wheel with a 300 pound load rating and airs up to 50psi. The only problem I have now is that when I am backing to the ramp, the hitch stays parallel to the roadway until my tires cross the incline threshhold. This means the coupler on the trailer will want to be higher. My trailer is heavier than it should be in the rear because the boat currently sits several inches too far back, so the tongue rises considerably off the ground when launching/retrieving.
Total cost was $75.