Using POLYGON for the tree only (NOT for the player) and c_setminmax for both is the correct way. Press F11 twice to check the bounding box of the player in the engine, it will be too big so set the min-max vectors of the player manually after his c_setminmax call.
"Falls das Resultat nicht einfach nur dermassen gut aussieht, sollten Sie nochmal von vorn anfangen..." - Manual
