If your son really hopes to play some WR or CB (hopefully he's fast), the learning curve relating to full-contact will be steep. There is some geometry and physics relating to the leverage of blocking/tackling, shedding blockers, etc. that takes time to become second nature. There are some decent non-padded summer camps and 7-on-7 tournaments that can help a bit in this regard.

The good news is this... football, more so than any other sport I know of, lends itself to good athletes with less experience still being able to be successful. There are tons of kids who don't play little league football that end up being top-notch HS players.

Good luck!