Question for savannah build

[Gaflem]

I am in the planning stage for an 8x4x4 enclosure and I have some questions. I agree for the most part on using 3/4 inch plywood except that I am going to make this cage with insulation enclosed by plywood on each side because it is in my garage. I was thinking that since 2x4 will be the primary support that I could go with 1/2 inch plywood except for the base due to the soil substrate I will be using. Will that work?

My other question is for the thickness of the frp I will be long the substrate level with. Looking online the nearest stores to me that carry it say to have only a thickness of 1/16 inch or 0.09 inches. I have seen others only refer to 1/4 inch but I have not found this yet. Will less than a 1/4 inch be fine?

Thank you for any advice that is given.