Making up some adjustiable rear sets

[Linden]

Basicly these will be 2 rectangles
FrankRearSets.png
1) 100x80ish to mount to frame with for and aft slide ie 6 hole using 2 at any one time at top and on 4 or 6 taped holes (Q2) to hold foot pegplate
2) 130x60 Foot peg (and gear level) mount with 3 (2extra for gear) tapped holes for footpeg and many holes to attach to mount plate

Now the question
1) thickness of Al plate 8mm or 10mm (or even 6 or 12) (need strength & plus meat for bolt taps but would prefer not to have to drill the crap out of it to lighten
2) bolts M5 M6 or M8

I'm thinking 8mm plate with M6 holes

this is the current bracket (without the lowering stuff) but that's the idea


Any thoughts ... little mick I'm looking at you here