Sealing a compost toilet with fiberglass
I'm finishing up my composting toilet and a thought occurred to me about sealing it. The box is built out of cedar, with an industry-standard 5-gallon bucket waste bin and an elegant porcelain urine diverter that takes the liquids under the bus. A small computer fan will circulate fresh air into and out of the box, under the floor.
Anyhow, I realize that in the real world, there will be occasional splashes or times when the bucket chemistry isn't just right and a smell develops. I'm concerned about the wood absorbing these liquids and smells over time. I was going to urethane the inside of the box, like the rest of the cedar siding inside. But I am wondering if it would be better to fiberglass the inside of the box for a more complete seal?
I haven't worked with fiberglass before, but this seems fairly straight forward. Brush on the resin, lay the fiber mat, and brush with resin. Repeat for a few layers.
Looking for thoughts on this, as well as advice for laying the fiberglass.