Brindle

Hi folks.
A bit of a query here again. I've searched for the answer but not found it exactly.
I am pricing a large ensuite, walls and floors. 21m ceramic walls, 8m porc or ceramic floor - cust yet to decide.
The substrate is very solid chipboard (recent new build), and runs through at the same level into the bedroom. Am I ok to tile the floor using Bal flexible providing I acrylic prime first.
I have a feeling the customer won't agree to adding another £200 for me to install tile backer board.
Cheers

Bob