Sounds like a decent approach. I switched from a 30 year to a 15 year mortgage as a first step. Later, I decided to sell off some stock to pay off the mortgage. Now I only have property taxes to pay on my primary residence. In February I purchased another house using just my state/federal income tax refunds as cash out of pocket. I still need to rent the place out. I've been too busy to get that done. It will only generate about $100/month above the principal/interest/tax/insurance, but I can write off the interest/tax/insurance and the principal becomes equity.
My property taxes amount to $300/month. Even when you own a property "free and clear", you are still "renting" it from the government on pain of confiscation for non-payment of property taxes.
300 / month property taxes on multiple properties in more than one state is not bad at all.