Well.... I'm probably not gonna give you a straight up answer, but we're close enough to share some soil types, topography, and weather patterns that have more in common with Missouri than they do with Dubuque or Champaign, so I'll throw out some ideas for feedback at least.   

1) Swath control does keep dollars in your pocket rain or shine, hail or drought.  My corn planter is driven by a Pro 700 but has row clutches controlled by a PP 20/20, and the acreage difference between them at end of the season is consistently at least 8%. 

2) I've been doing my own soil sampling since about 2005 when I was using a rather crude HP Ipaq for mobile logging.  Now that everybody is walking around with convenient GPS in their pockets, there are several platforms for DIY sampling that are a great return on your time, assuming you already have the ATV/UTV to go to the field with.   It's nice to have a baseline on a farm new to you, and is definitely good to find out if there are specific places that need a pH adjustment.   That said, there is no amount of fertilizer that will turn 80 bushel corn into 220 bushel corn if the underlying limiting factor is usually too much water.  Bringing me to....

3) Now there's a tile plow, excavator, trencher, and scraper sitting in my yard.  I kinda thought you were already mapping with a yield monitor, but maybe not, if so developing some history there will definitely help prioritize places to emphasize drainage.  I'm going to re-assess how I do some fertility on farms that go from wild variability to more consistent yield maps.

There's a pretty big time sink involved doing this stuff with limited manpower, but it sure is a more satisfying thing than trying to farm too many acres with that limited manpower and knowing at the end of the season that you didn't do as good a job as what should have been.   Bits and pieces of these will go further towards your last point than trying to save up change in a piggy bank, you are doing well to think about what returns the most to your time rather than doing things that are kinda more fun but are really minimum wage skill jobs.