Bonnet protectors and Dual dattery system 100/105 LC

G'day a couple of questions
Have had problems with non genuine bonnet protector fitted to a 2004 100/105 Landcrusier they seem fine at moderate speeds but at 100kph for 30mins the outer edges come unclipped and start flapping
to the point where 1st one broke had it replaced and replacement has just done same thing so had to remove it.

I know this could be opening a can of worms but here goes can i get suggestions and feedback on a dual battery system to fit to 2004 100/105 series Landcrusier

Cheers CD