I assume sgma is standard gauge modular association.
Only problem I've had with drilling is finding the hole after I drill it. The astroturf immediately hides it. So I stuff a pipe cleaner in the hole immediately after drilling.
You can use fake Christmas tree branches as trees trimmed to the desired size and shape and just shove the metal shaft in a drill hole through the astroturf. If theres a clearance problem you can just bend the metal "trunk" to change the tree shape.