If that’s a photo of the actual shoreline, then your basing is spot on Rich, in fact perfect!
But I understand what your saying.
As I recall some fellows made it up the beach to walls and ditches?
It’s a trade off between what is historically accurate and toy soldiers isn’t it?
Assuming you want to use them for other ‘roles’ and events, why not stick some of that spikey sand dune grass on there?
The odd comedy red crab? Seaweed?
Puddles of water, or some bigger rocks?
The first thing I’d do, is give the bases a wash over with a darker colour then dry brush back up to pale. This may give more contrast.
Anyhow, your work is inspiring...