This link, if it holds up in this cut and paste, should take you to the satellite image of the site. The church appears to have been located along that farm track going south-southwest of the farmstead in the center of the image. Roughly, perhaps, where the Sniabar juts out to the east.... And while the precise church site may be difficult to locate, that field and the surrounding area were likely where the skirmish took place. Please let us know what you come up with.

http://maps.google.com/maps?q=wellington,+mo&hl=en&ll=39.121571,-93.965807&spn=0.009988,0.019763&safe=off&hnear=Wellington,+Lafayette,+Missouri&t=h&z=16