What REI strategy should I focus on?

[Jorge Gordon]

If there was a "FIRE" forum I'd put this question there....

My mid-term goal is to diversify my income, not be as reliant on my current W2 (~110K / year), and set me up to be very flexible in what I do in the future. I think a reliable net $2500/month in passive (to the extent that really exists) in the next 3 years is a SMART goal. That and my wife's much smaller income would provide cushion and runway for future entrepreneurial opportunities, taking lower-paying W2 options that have higher long-term potential or are just more fun...and worst case scenario this would be more money to save and snowball....

What I have to work with is about $200K in mutual funds and 4 doors (two 2-bed SFR owned free and clear each renting in the 600's, and a duplex mortgaged conventionally) that are all nicely cash flowing and gained equity in my ownership. I could "monopoly trade" into something bigger, and I consider them good for at least $600/month (I'm conservative). All are actively managed. I've done a couple of flips. I have a lot of managerial and project experience. We've been making efforts to reduce our major monthly expenses (down sizing house, etc).

So what has worked for you?  What do you think is the best strategy to employ my capital, ability and time here?