The Brits have come up with a device for launching and recovering a relatively large motor lifeboat over the beach. The boat in question is 18 ton, not much smaller than a 47 foot MLB.
Certainly the Coast Guard has a number of trailerable boats, but I don’t think I have ever seen anything like this.
We have this beast for the bigger boats as well
http://www.thinkdefence.co.uk/2012/08/the-beach-recovery-vehicle/