It worked for a year without the solid mount. Just had to retape it a few times. No big deal. The insulation is fairly flexible.
The solid motor mount has many other benefits and no downside that I have found yet.

PDad and I have near identical mods except he was running with a gutted box and me with the CAI Cone.
Mine was 3/10th'* faster in the quarter because of this...........and also having an off road pipe.
About 20 hp in my estimation.
It made the same difference as carrying an extra 160 lbs of weight.