Prolly a safe bet installing them as forward as you can get.
I've seen the timber/ice age combo stab a track. Wasnt pretty, cut the track in half. Had to rip down to the truck, go to town and buy a track, toss it on the back of the tunnel, ride 26kms and install the new one on the hill. A day of riding lost and 900 beans for a track. Costly day for my buddy, could have been worse if he was on the pipe @16lbs, cause if that track would have stabbed at that time he would just be landing. lol
Ive installed 3 timbers this year, all with the one limiter, and all are fine to date. (Personally, i would like to see 2, but thats my own opinion).