Chiefston, fantastic mod! I have never done any project like this, and it was very easy to follow and do myself. I did make a "mod" on your mod.
For starters, I have the 12 gallon and didn't have any problem with lighting the bottom of the far corners. However, halfway up my tank on the front the lighting ends. But fortunately the front usually has low lying plants anyway.
Also, because I have 12 gallons, I literally just doubled the LED's that you had put on (8 Cool White Cree XP-G's and 4 Royal Blue LED's from the Moonlight Kit).
My tank came with the stock 42 LED's (5 watts... the newer lighting they added). The main difference between my mod and your mod is that I wanted save the entire stock arm to be able to reuse it if necessary. So, instead of cutting the lights out, I made some arms out of some aluminum channel.
Lastly, for anyone making this mod on the 12 gallon, I used the Mean Well LPC-35-700 driver (which kicks out about 35 watts) as my driver. However, normally I would have used the Mean Well LPC-60-1050 which would kick out more like 50 watts which would have worked very well with my LED's, however, I'm running shrimp and Cardinal Tetra's (both of which don't like too much light). As a result, I went with a little lower lighting (but still enough to grow my plants... well, hopefully!). If nothing else, my tank now has "wings" from the great lighting!
Anyway, you can see from the photos that I put in (2) 1" bolts to catch the arms to keep the lights set in position.
Anyway, thanks again! Great modification! Works like a charm in my 12g Edge!