I've run regions at that tax with those conditions as well as other class combos. The main things are that you'll likely spend a lot of time in your region, and you have to beware other factors causing trouble. It's very possible to maintain and even bounce back by yourself, but the perk of the high taxes is that you can ideally afford to pay knights to keep your (and their) income high.
I know one of my characters is in a crippled realm, and he and other people do almost nothing but regional maintenance so people can run insane taxes.
Hell, I remember running a 99% tax in a region once when it was possible. It took some big hits on regional stats, but nothing that made you freak out about revolt before tax day. I've even ran trades to give negative thousands of gold- destroying all infrastructure and giving everyone negative income. Like everything, you live and learn..... and drink vodka.
