Are you going to thru bolt the handles to hold the louver on? If so don't use those templates. If you are let me know and I will give you an idea to mount them without the holes being on the very edge of the under hood braces.
I'm not sure about availability of the OEM sliders and Ridgedemon is on hold right now so I will share the Rocky Road idea with you if you are attempting to make some.
I added a strip to the bottom of them to protect the body seam. There is a place on the frame for a 4th bracket. I don't think it was because they missed the mounting holes because they are under a sticker but rather they thought they were strong enough without them. I don't know about that for sure and have thought about making spare ones since they did not want to sell me extras at that time. Never made them but the strip idea I did in 06 seems to help stiffen them. I use 3/8 by the length you want.
I have used a hi-lift on the side of them and raise both wheels off the ground with mine and slid down some rock ledges with them.
You might also want to look at this.
http://www.hummer4x4offroad.com/forum/showthread.php?737-Hunner-rear-wheelwell-body-seam