Let's talk dirt

Your plan seems reasonable to me. However, “pretty” roofs aren’t the goal. Extremely water resistant is the goal.

When I really need a deep clean on my fiberglass roof I use powdered comet with a scrub brush.

I use a long handled brush with detergent to clean around vents, a/c etc. and power wash the rest.

Lwiddis wrote:
Your plan seems reasonable to me. However, “pretty” roofs aren’t the goal. Extremely water resistant is the goal.

My Roof was Bright Tec (one of the rubber roofs)

I treated it just like the kitchen floor with some minor changes.

2x a year I'd go up with a mop (or Long handled "Van wash" brush more often than not. this is a telescoping handle car wash brush. Flow through though that feature is not needed)

A bucket.
Spic and Span (just like the kitchen)

A garden hose with sprayer.. charged (pressurized)

and optionally a broom (The brush can double as a broom)

Brush all the loose stuff off. do an initial inspection.

Fill bucket about 2/3 with water and Spic & Span (I liked to go a bit heavy on the cleaner)

Then starting as far from the ladder as possible mop a 2-3 foot swath. hose it down, next swatch, hose it down and so on till I was standing on the ladder doing the last little bit.

You should then (next day) do a second roof inspection.
With rubber I did not treat. but with fiberglass... Might be needed. I'm not an expert on fiberglass roofs.

A little bleach in the wash will do wonders for killing the fungus growing on the roof.