Carpentry and Woodworking - A Protective Plywood Shroud for a Mower

Here's the problem.

My parents backyard is big. Its also a mess. Lots of
bumps, lumps, bare patches, and weeds.

I've got one of the more powerful walk behind mowers.
It has a high tunnel deck. Unlike some mowers, the
mulching feature works well.

My parents tried a yard service before I started mowing.
The first time they came you couldn't tell that the lawn
had been cut! My dad asked them to come back. He
doubled their fee which didn't help much.

Last year I was constantly cleaning and repairing my
mower because dirt would almost bury the motor each
time the lawn was cut. My first thought was to build
a protective shroud of some kind. The tunnel deck
is full of complex angles. I tried making a pattern
with foamboard. My plan was to build a frame from
thin plywood and cover it with a couple of layers of
window screening. That would deflect or trap most
of the dirt, while still allowing the engine to breath.

I played around with the foamboard for hours. The
complexity of the deck made cutting a pattern almost
impossible. I gave up. A week or two from now I've
got to start mowing again. As a joke, I told my dad
I'm going to spray the entire yard with weed killer.
Maybe that's what I should do!

If you've had a lot of experience forming complex
patterns maybe you can give me some advice. I want
to build a shroud, but can't figure out how.

What about buying one of those mowers that you drive or remove all the grass, cover it with artificial turf & donate the lawn mover to charity?