Per your PM, I think I know what you're asking now.
Yes, the "mostly-agreed-upon" width of the lip is 1/8". However, I'm not sure how brittle/flexible the MHK resin material is, so you may have to make adjustments.
On my fiberglass bucket, I sanded the backside of the visor area to 1/8", or close enough. As long as it's uniform and looks good, I think you're okay.