removing the windshield can turn into a can of whoop azz real fast if you got rust.

seems all the cab rust starts at the roof drip rail/glass/gasket pinch weld and runs down the inside to the bottom of kick panels. also rolls down the inside back of cab keeping the seatbelt wet. cargo light never seal either.

6 gallons of bed liner inside and out.

so..YES! you CAN "JUST" do it from the inside cutting the gasket.