I have quite a bit of extended family that operate small farms. The one who actually does it for a living without another job has around 1000+ acres and is NOT rich. You'll never make $25k from a 10 acre farm, the rental property is more promising, even.
There's quite a bit that goes into it, too. Whether you're growing vegetables or raising cattle, the market is fierce and you need to be well-educated or you'll get destroyed.
I have a friend that makes $15k annually off of a couple green houses that probably don't take up 1/10 of an acre, but he does run wide open for 3-4 months durning the spring planting season and has to deal with freezes, bugs, etc. With two adults and a hard working kid, I am sure he could scale it up to $25k a year on less than an acre.
I have another friend that makes a meager living (a few years back he told me $12k taxable for a family of three, but I think he is doing better now) off of around 5 acres of berries by selling Jam made from the berries.
It is doable, but as others have mentioned, it is a lot of hard work that has to be done "right now" or all is lost. I recommend reading all the Joel Salatin you can get your hands on. Small acreage can be profitable using the following principals (some of which have already been mentioned):
Labor intensive (not land intensive) crops (made better by access to intern labor)
Agroturism
U-Pick operations
High value crops
Direct selling (made better by access to high cost of living markets)
Value added of Organic (certified or not)
Out of season production (everyone is selling tomatoes in July!)
Keeping production costs low by sourcing local, used, materials.
We've been small scale farming for over 10 years now, and I have yet to come across anything that I would feel confident enough to be reliably profitable year in and year out, as almost NOTHING has produced as expected. We have battled voles, rabbits, groundhogs, parasites, hawks, rats, drought, flood, frost, fungus, blight, etc, despite picking ventures generally considered reliable, not longshots. And while most of these things can be mitigated, every nickle spent, every loss, and every hour worked eats into your return, until you are working a sub-minimum wage job. While I still love it and don't mind working for nearly nothing on my terms, I think it would get real old if I HAD to do it to make ends meet, not to mention the stress, which would defeat much of the reason for my ER persuit. You can end up feeling just as trapped on 10 acres as you can in an office. BTW, 5 acres is MORE than enough to keep a family very busy if you are doing almost anything besides mechanically farmed row crops and/or pasture.
Once I ER, I will probably spend some time marketing some of our products, but I will not be reliant on the income in any form or fashion and will remain at liberty to cut anything at anytime if I am not enjoying it.
Sounds like you and your wife have pretty good jobs. Nobody knows what will happen over the next ten years, but ten years ago, I would have never dreamed of where I am today. Keep saving and investing and you might not even need to generate additional income.