which commander did you use? sabrina and erin and some bushes make every tank a lot stealthier. i know that are not commanders that are normally used for T15 or arty, but if someone has reasons to try to not get spotted why not to use them, also the retro that gives better camo if the tank does not move should help.
my T15 with a commander without camo bonuses has 12% camo
with erin and absorbing paint v2 gets 17%+8%(paint)=25% and gets also a 21.7%bonus to the foliage camo factor, behind some bushes it becomes a pretty stealthy tank.
i did not try myself that position so i can not tell if the bushes, that cover well a sphinx, are too small to cover tall tanks like the t15 or the arty, but before being sure that the position does not work a try with the right commander and the paint retro has to be done.