There is a good argument for using the closest station as long as it is serving up accurate data.
Check the data of a station using http://weather.gladstonefamily.net/cgi-bin/wxsite.pl?site= so for D0517 here is the quality data. http://weather.gladstonefamily.net/site/search?site=D0517&Get+information=Get+information
You can also compare a station with other stations so again for D0517 here is the results http://weather.gladstonefamily.net/cgi-bin/wxqual.pl?site=D0517
If the station is not getting a good MADIS rating, i’d avoid it. On the other hand if it is closer and has high ratings, I’d be okay with it.
I use my PWS for my data–it’s close and accurate and the nearest commercial station is over 10 miles away with often much different weather.
Looking at the cocorahs.org data for Madison county for April 1 shows a wide variation in precipitation for that day making the case for closer is better.
Good luck.