My bowl is currently designed as such. its half filed with java moss and the other with Rotala, which is trimmed back every 3rd week and replanted. These stem plants have kept the moss on their side of the tank while giving the shrimp variety in their environment.
I have left open a small 3" diameter hole for a feeding bowl where i concentrate the food deposits. this also curbs the amount of detris vacuuming during my WC.
I have only used the fluval substrate once and probably will never use it again in any other tanks. its light, easily disturbed and difficult to plant anything without having more than an inch depth. the shrimp seem happy with it but they arent ensuring things look pretty
I thought of leaving in a branch of driftwood but it only makes maintenance a pain so i decided against it. hope it works for you.