Chris - you need to do some initial sanding of the filled area, then "guide coat" with sanding primer and sand that nearly off - doing that repeatedly will let you see those waves and gradually reduce them to something acceptable as a starting point for the paint job .... also primer is a must before any paint, even temporary, and a thick sanding primer is better than spot putty

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot