We don't do it exactly how you do it, but I've been playing in leagues that have a MiLB draft for about 5 years now. Following the minor leagues is very time consuming, but I've found it to be a ton of fun. To the point that I'm just as likely to guy to a MiLB game to "scout" my players as I am to watch my guys at a professional one.
Baseball America is a decent source, as is Kevin Goldstein at BPro, Jon Sickels, Keith Law at ESPN, Project Prospect, Scouting Book, heck even the Shandler's Forecaster does a MiLB ranking. There is tons of information out there.
Obviously, you don't have the time, and you probably don't have the skill, to scout these guys yourself (I certainly don't in either aspect), so you end up relying on their rankings to a certain extent. Personally, there are commentators I like more or less than others and rely on them a little more frequently, so I create a weighted mean spreadsheet from various sources. Then I make adjustments to the lists based on certain statistical categories (K:BB mainly) and which tools the prospect has that are considered plus or not. For example, guys that are considered to have a plus hit tool and a plus power tool (60 or better on the 20-80 scouting scale) get huge jumps in making rankings whereas guys that have plus gloves or plus arms get bumped down. Pitchers are a bigger injury risk in MiLB than in MLB, so they generally get moved down my list as well.
In my fridge: Founders Kentucky Breakfast Stout (KBS), Central Waters Peruvian Morning, Bell's Batch 10,000, Dale's Pale Ale, Capital Brewery Amber, New Glarus Moon Man, and Guinness.