I use a piece of the perforated aluminum metal intended for leaf traps over household gutters. It's much thicker and more durable than window screen, and it's pretty simple to cut and form it into an acceptable-looking strainer screen. Wrap it over the outside of the pickup can and secure it with a big radiator hose clamp. It will strain out the rocks, marbles, and other big chunks that could damage the oil pump gears.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!