I can't recall the details exactly but the 1G Sprinter I had, had clearance issues, may not be as bad as yours, but the actual rib part of the reinforcing (not the flat) was cut and removed then filled in with smaller parts to make it an indent ans more factory like.
Whilst yes it does change the strength of the bonnet (from an engineering standpoint) the effect is more like adding another point of flecture (crumple zone) in the bonnet.
I'd keep away from having to do it through every rib if possible.
Cheers
Simon
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