Best heat insulation and source for Predator 212 ?

I am using the stock OEM muffler that came with the motor and when riding my Mini Baja my left inside thigh is very warm almost to the point
of pain unless I shift to an unnatural position on the bike. It looks like I have about a quarter inch space between the muffler shield and
the muffler and I was hoping to find some kind of material to stuff in the space instead of just using the air....

Other ideas are to sew a dinner setting placemat to the inside left leg hamstring of my riding jeans .....

Other recommendations ?
The place mat sounds like a good idea. My recommendation, however, would be that you hide the corresponding dining table chair behind the garage so the missing place mat won't be noticed...
That tin foil looking stuff at Lowe's you could cover the shield with a piece of that maybe stuff some between but it would hold the heat in if it's on the outside kind of extra guard then that little bit of space could still flow air

or the other would be header wrap and if somebody calls you out on the ace bandage on your pipe tell them you crashed and it had a boo boo
I am using the stock header and muffler that comes with the Harbor Freight 212 Predator engine. It is like a square box muffler and there is no adjustability to its attachment. The alternative would be to buy a separate header pipe and attached muffler of some sort which would cost more than the entire price of a whole new engine.