Here is a standard defence in depth vs F/T (or anything else for that matter)- let’s assume a 7 stand grenadier platoon.
In this photos the Soviets are attacking from the left. The AT gun HQ and 2iC are probably a bit close- you want them about 3" behind the picket so that if the picket are engaged they could die but the 2iC and AT gun commanders are close enough to become involved in the combat in a counter attack but not targetted as they are not going to be within 2" of actual assault on the first contact. also by having the 2 pickets about 5" apart the flamethrower can not move between them (they both exert of 2" zone of control).
Now even if the 2x pickets are roasted the 2iC and/or AT gun commander will be dragged into the combat and the 3x pak 38s able to fire at full rate of fire (assuming they are not pinned).
Now if you do this defence with 2x interlocked platoons it becomes even harder to crack as one picket will be from each platoon and the flamethrower must target one or other platoons so you only risk losing one team but having a lot more defensive fire capabilities.