This is how it would look!

A U.S. Navy landing craft utility (LCU) from USS Pearl Harbor (LSD 52) prepares to move equipment and personnel ashore for Pacific Partnership in Tonga. Working at the invitation of each host nation, Pacific Partnership is joined by partner nations that include Australia, Canada, Colombia, France, Japan, Malaysia Singapore, South Korea and New Zealand to strengthen disaster response preparedness around the Indo-Asia-Pacific region.(U.S. Navy photo by Mass Communication Specialist 2nd Class Tim D. Godbee)

An LCU stops far short of the beach and discharges its cargo.

This is how the concept would work if the Marine Corps adopted this method to achieve over the horizon surface assaults utilizing both its LCAC/LCU and Marine Personnel Carriers and Amphibious Combat Vehicles.

The Ships would launch its LCACs and LCUs from over the horizon to a predetermined set of coordinates...they would discharge the first wave of vehicles.  For the second wave the LCAC/LCU would make the entire run to the beach and we would use airpower and naval artillery to keep the enemy away from our landing area.

Additionally the first wave could motor inland and establish a different beachhead to keep the enemy off balance.

The whole point of this is that we have the tools necessary already.  We don't need to make the same mistake of designing a high water speed amphibian.

First select the right vehicle for the MPC and get it into the fleet asap.  Next decide what you want in an ACV but understand that we have workarounds already on hand to negate the need for high water speed over great distances.

WE CAN DO THIS NOW!  We just lack the leadership with the vision to get it done.