Tirailleur - Blow up outpost objectives without being detected

I don’t know if this has been covered on here; but I’ve googled and googled to try and get this challenge done. Spent over 12 hours and must have cleared this village and blown them all up simultaneously nearly 40 times; but still not got the challenge.

2 sticky bombs on tank, no matter placement does not work for me, wtf are these tanks made from. Tried both on front, 1 on front & side. Both on back, 1 on side and back, 1 on each side, 1 on turret & back, both on turret, 1 on turret & side etc. 

I have tried the placing 2 on each gun, then on tank and shooting sticky bombs with both rocket launchers you can find, neither worked. 

Lastly on forums was placing the 4 bombs. Then throwing an anti tank grenade at tank, forums said between 1.5 & 2 seconds detonate; but whenever I do it, even if as fast as I can. I still do not get the challenge flash up. 

I even tried putting 3 bombs on tank, 1 on gun and then throwing an anti tank grenade at third gun and detonating within time frames.

Any help on this would be appreciated as I enjoy playing games trying to get 100%, and if I can’t there’s not really much point anymore trying to get the others. If a patch will come out later to make it so the 4 bombs destroys all, or a better description on how to do this I can move on and come back to it; but I’ve had stop playing and moved on to something else as annoys me knowing I’ve got everything so far; but that one as it’s either broken, or am I not good enough, even after 40 restarts and over 12 hours of that level lol