i allways assumed the tension rod ran down a slot that you would cut into the neck face and cover with the fret board ?
wouldnt work if your just adding a veneer as the fret board

i would s**t myself trying to drill over that distance

you have got me thinking now!!

if the standard is to bond your fret board over the slot then it would be easy .....

iv just measured one of mine.... the fret board is 5mm deap, rose wood i think