I'd call Disney dining and see what's available. Yes, you can dine anywhere on property even if you aren't staying onsite. The trick is going to be getting an ADR. Your options amy also be inside one of the aprks, so if that's the case, you'll need to pay for park admission.
One CD that is often overlooked, and maybe even doesn't take ADR's is the character dining at the Swan. The character interaction over there is pretty good too! They have a character breakfast in the Gardne Grove (they used to have a character dinner, too.)
Garden Grove DOES take ADRs...but the three times we went there you wouldn't need them! (Though I'm one of those "better safe than sorry types, I'd make the ADR since I know I want it.....but it's also one of those that I feel confident I could walk up and get).
And it's a great character experience, a lot of it because there isn't the large crowds so the characters can spend quite a few minutes with you. We went for an early dinner one Friday evening and the characters were Rafiki and Timon (Lion King).....we were literally the only table with kids....and our first plate of food got cold because the two characters were playing with us and we were having so much fun for probably 10 minutes or more. Now...once other families arrived, we didn't get that kind of attention, but they came around a half dozen times while we were there. And the food was great. TImon & Rafiki were only there Mon/Fri night, so be sure to ask if it's a night for them.
THe weekend breakfast is also wonderful....the characters were Chip & Dale, but I hear that Pluto and Goofy are sometimes there too, and again, a lot of time spent at each table. Great food.
Only downside.....you have to pay $10 for parking (AP and DDE don't get you free parking)....also because Swan is not owned by Disney it doesn't accept AP or DDE for dining discounts either....but our
AAA worked.
Other great character meals for a boy (i.e. not princesses, lol):
Crystal Palace with Pooh and Friends (this one is popular so may be booked since you leave so soon, but ask, sometimes off times are available.)
Animal Kingdom has characters at Tusker House (Donald's Safari breakfast) it has Mickey, Pluto, Goofy and Donald....maybe Minnie?
Chef Mickey at Contemporary Resort may be very difficult to book this close, but it's excellent and has Mickey and friends. Call and see if anything is available....lunch and dinner are supposed to be excellent too.
If he likes Jo Jo or Little Einsteins, then Hollywood Studios has a character meal with Playhouse Disney....no clue on the food as my kids are older.
O'Hana at the Poly has Lilo & Stitch, plus Mickey was there for our breakfast. Fantastic food, not a buffet in the traditional sense....they bring a platter of food to you and you can ask for more of anything. The juice is to die for....they finally brought us a pitcher, lol.
Bring along an autograph book (you can buy them at Disney, or they're cheaper if you get one before you go). And your camera!