Have you considered using a rockwool slab, cut it in half it would be about the size of your drip tray. Will hold a lot more liquid than just the blocks on their own.
I have spotted something I need to point out as I believe its a fire hazard waiting to happen.
I spotted a fan heater or fan blower sat on top of a cardboard drinks holder. If you use that type of electrical heater element blower they get hot, I have even seen one set fire to dust on the elements and burn itself to a melted mess on the floor years ago.
An elctrical heater like that really wants to be stood on a fire block, a brick, a breeze block or chunky peice of wood, not anything that is easily combustable or can crush and the fan tip over facing the carpet floor.
I only point it out as a safety tip for you @Growinnblowin I enclose the pic I spotted it in.