Wow, sounds pretty cool. I've done something similar on an 8x4 foot terrain.
I'm not sure if you've considered it or not there are many aspects of the battle that could have ended in disaster for the Marines.
There was almost no communication for the Marines on the first day. The amtracks were supposed to get over the seawall but didn't. The 1st amtrack wave landed fairly successfully because the Japs were expecting the landing on the ocean side.
Twelve Shermans attempted to land but only 3-4 made it.
The entire Japanese higher level command were wiped out by a DD 5" air bursts when they came out in the open. The is probably the reason for no night counterattack which most likely would have ended the battle.
Since the island is so small almost every Jap defensive structure will be in small arms range of any Marine unit. However, since most were at ground level their FOF and LOS will be restricted to short range. How short will be your decision. There were only a few structures above ground.
The larger command bunker on Red 3 held up 2/8 until a lucky hit from an 81mm mortar round the went down the rooftop mg position, exploded inside and touched of the ammo. This allowed Lt Bonneyman and his assault team to start destroying it but it took hundreds of ponds of C4.
Decision Games version of Tarawa is well done and handles the FOF issue on the map in a visual way. It's a card activated game so it takes into account the problems and what-ifs related to the battle. I know the game and map designer and they are the best in the business.
link
Wolfhag
finds bridges to match the river sets.
