While I'm not typical, I think there are a good number in a similar position:
I've got a house with a roof approaching it's end of life. I use 4MWh/month. My electricity bill goes between $1.2k and 2.4k. A Solar City roof is about equivalent in long term (20-30 yrs) cost with a much better warranty.
28L was dark apart from the X, and the taxiway was lit (albeit with taxi Lane instead of runway lights). Expecting two lit lanes and approaching the one on the right, they certainly saw something "off" but this wasn't a case of pilots choosing to avoid the only lit lane.
If you're looking to add a checksum, why not use an existing format that does things like variable precision and proximity well like geohash (http://en.wikipedia.org/wiki/Geohash) and just tack on a checksum digit?
"ezs42cw4" becomes "ezs42cw4 f3" and my client can generate the checksum for me so I just have to verify, rather than enter the last two digits.