Unanswered Variable infill?

I think there's probably not a way to do this, but I have a large part that takes a while to print, and I'd like to print the first and last 10% at 100% infill and the rest at 10%.

I know I can alter the printer settings for solid layers, but if there's any way to avoid that, I would prefer it.

I need to put screws into the ends and with low infill that's a problem, there's nothing for them to get a grip on.