asf rack mesh size

I am making an ASF rack. I am using full size steamer pans (13"W x 21"L and 6"D). My question is how small of mesh can I use and the asf's still able to eat through. I was using 1/2 x 1/2 and the little darlings went through that. I reall want to sue the 1/4 x 1/4. Will this allow them to eat? Are the tubs big enough for 1:3? I am not sure if I am going to have wheels in there or not but with the steamer pans I have NO worry about them chewing. I was thinking about putting heat cord around the pans in the winter. So any help would be great. Thanks.

I use 1/4 hardware cloth for mice and ASF, I use 6 and 3/4 inches deep tubs which allows me to have a wheel.

i havent had any problems with 1/2", i use 1/4 on my grow up tub just because thats what i had because i was making hoppers for the new food. the tub should be plenty of room for a 1.3 group