Not amphibious, but there was a river crossing involved, the Battle of Long Tan was turned by the arrival of a troop of M-113 APCs and an extra company if infantry. During the Vietnam conflict Australia never deployed more than a Squadron of tanks, the USMC I believe would deploy six Abrams with an ARG.
We are talking about raids here, the whole concept is about over match at a specific point, hit fast and hard and get out. Trying to remember where I read it but for raiding it was common for Commandos to bomb up with additional GPMGs, 84mm Carl Gustav, mortars, even Milan. For a company strength raid it was not unheard of for them to deploy more fire support than a battalion.
When you are hitting then bugging out, rather than trying to seize and hold ground, weight and volume of fire is more important than the number of boots on the ground.
Thinking on it, an AEV or breeching vehicle could be even more useful than an MBT, maybe a modern day AVRE with a demolition gun, or a modified MBT with appropriately trained crews and demolition munitions, as well as multiple RWS and active defence systems.
Heavily armoured, draws enemy fire, absorbs damage and takes out strong points that could hold up or pin down the Raiders. Seems worth the effort of getting a couple ashore.
As to how, the RN wants to use the bay class for this mission, i.e. Combat boats, LCVP, RHIBs and helps to get the troops ashore, LCU for the armour. Going forward, it wouldn't be that hard to incorporate a docking well into an Absalon type multi role vessel design for a single LCU or LCAC.
