B4 was never available to the Tank Hunter Tactics commander.
Imo a "tank hunter" commander should not even have access to any sort of AI howitzer in the first place.
IMO, it is more of a bait for enemy to dive for. You set it up somewhere next to frontline, heavily saturate area with mines - both cheap and heavy variation, place a couple of cons with PTRS upgrade around most obvious routes, and then start firing with howitzer.
Enemy immediatly starts to crap their pants, screams about "artyfest" and tries to destroy your howie. And thats where your traps come in.
However, idea of 400MP 40FU bait for me is rather strange - especially if enemy can just nuke it from orbit with stuka dive. Also, the ammount of troops you need to pull that off without loosing mapcontrol is enourmos - about 5 cons, 2 mg, at, 2 engies at very minimum.
So, yeah, B4 might be more straightforward and effective approach - maybe even too effective. I would switch howie for tanktraps as more fitting for theme of doctrine, and maybe switch out PTAB bombing run for AT overtwatch. Not very efficient, but true to theme at very least.