mine didn't come with a template. i would trust the masking tape routine. after putting the rack over the masking tape, you draw around the racks legs, then drill. i agree it is probably more accurate to do one leg at a time. you don't get a second chance, so measure twice and drill once.

 

https://www.hdforums.com/m_1687102/tm.htm

Mine came with a template. Use it to get the front to back centered between the passenger backrest and the trailing edge of the tour pak, you can eyeball the side to side centering. Use masking tape and as you've already seen measure over and over. After I got the first hole I even measured diagonally. I changed out the hex bolts for a round headed bolt so there wouldn't be any catch edges inside. Loctite everything.

Arvid

 

Thanks a million.. I'll give it a shot!