Wow sounds like me..I coached basketball for 10 years then started coaching football..same thing my defense out shined the offense so I was begged to come back.. I learned from basketball you can teach anything its how you present it ( people said you can't teach the kids the flex offense its to hard)..so the gap 8 is good, don't choose it cause it is easy to teach..look at the 50 if there is mainly run teams in your league..me I use 4-4 switch to a 6-2 also i stack my linebackers alot in the 4-4...this year I might try a 3-3 odd man stack...but I was able to teach the kids with great ease..(gap assignments) defensive techniques..some parents complained that it was to much but once they saw how easy there child understood it..then they became a fan..sounds like your on the right path..starting early...what ever defensive you choose...challenge yourself..How can I make teaching this fun,easy to understand & still have a disciplined defensive unit.. good luck on your upcoming season coach