Yeah they dissapeared from the radar ,..i would really like to see a built up.
I informed about the sturdiness of the legs(at-at) since i woried about the same thing as you.
The solution to the problem was that the legs would be casted hollow so that the resin would be much less likely to warp under the weight of the body,..i asume the at-st has the same leg construction.
I imagine that 4walls with air between then is indeed sturdier and more heat resistant than one solid piece of resin.