Ask the customer to accept that this won't be stacked--use the cake stand that holds each tier separate.
Make very rich biscuits using a scone recipe that won't crumble as fast. Bake in pans in 2 thin layers per tier.
Make a strawberry filling using firm gelatin (3 ounce pack jello and 1.5 cups total liquid) to hold the berry slices together. Prechill 1" deep in the same pans as the scones.
Make a vanilla bavarian filling also chilled 1" deep in the same pans.
Assemble per tier, a scone, a strawberry layer, a bavarian layer, a scone.
Top with stabilized whipped cream and pipe decorations. Add strawberry slices in flower patterns...