Is that about 1v1 mode? Not really a 1v1 player, but I'm sure it won't work against decent Wehrmacht player.
Your opponent will get better map control while you are sitting on 2 mortars and you won't see Stuart anytime soon. Instead there will be 444 which will rekt your REs, mortats and probably Cpt too.
In 2v2 this may work if you will be supported by your teammate.
In 4v4 it won't work, because once your mortars will be pushed out by Kubels/SPios/Volks/Grens you'll lose fuel point on your "lane" and won't get it back anytime soon because of long retreat path, so again no Stuart rush. REs just won't cut it.
Yes, this is a tandem 2v2 opening, also ive made it work consistently in 3v3 and 4v4, meaning 1 goes full screening infantry while you nuke the enemy infantry, grens and sturms WILL die if they bumrush the double mortars, even managed to force retreats on sturms vs RE's with volley fire, not cause of the RE's themselves, but cause suppresed infantry at close range is 100% dead next mortar autofire shot.
If grens try to shoot it out from cover, they will die to mortars in 2, 3 shots at max, the trick is placing the mortars forward, their accuracy is pretty much 80% at medium range.
Couple dat with an ambulance and you can reinforce cheaply with RE's AND heal endlessly while you nonstop bomb the enemy at a rate and accuracy they cant compete with.