You've got tough stuff to deal with. My yard is grass and weeds and I scrape the decks out once a month or more often if I have had to mow wet grass. I don't know of anything to put on the decks that will resist everything from sticking.
Went all out this time. Bought Por15 to redo my blower. Had more than enough for that job, so decided to do the mow deck as well. I had been using the water cleaning port on the 54 deck. Had used the graphite paint in 2014, which did pretty well, but came off. The water port kept the deck surprisingly clean. So cleaned it up with a wire wheel. Scraped a lot of the paint and rust too. Washed it with the de-greaser then rust converter washing the deck between, then letting it fully dry.I clean the MMM often thru out the mowing season. It surprises me sometimes how much stuff can build up. Getting rid of that build up is key for keeping my deck in good shape I have no rust issues. I might just wire wheel and wipe with oil when I switch to snow blower and skip painting it this year.