Rollback marker light grommets?

I have an aluminum rollback that I need to run new marker lights.

What they had on there they just had a tiny hole drilled for the wires to go through. I would certainly think eventually that will rub through and cause problems so for those that have run these before what type of grommet do you use?

My question really is because what you're drilling through on the aluminum rollback bed is pretty thick. A regular grommet like you use for a tail light in a tail light housing or something of that nature won't work, because that's only made for thin sheet metal.

What's the best way to run this and protect the wiring?

 

So just to be clear, you're saying that instead of actually drilling a hole and putting a grommet, I can drill a hole and use the heat shrink as the buffer against the wire chafing.

That sounds like a very good, simple idea.