A few random thoughts:
I wouldn't not do something just because it wasn't the ultimately best answer. Very few of us here have found the ideal solution to educating our HG/EG/PG kids - if you feel like your ds would benefit from a two grade acceleration, and only a one grade acceleration was offered, I'd go for it.
I wouldn't shy away from talking with the school about the need for more challenge simply because it's a private school and your ds is on scholarship. Clearly they must have wanted your child to be at the school if they offered a scholarship. Also remember, what you see looking in from the outside at a private school might look quite differently than looking at the situation from the perspective of the school's board or financial situation etc. They might actually *need* or at least benefit in some way from having your child enrolled. Obviously it's going to depend on the school, but it's possible they may really want to work with you.
This is just *me*, but fwiw, we chose to subject accelerate and after-school rather than grade accelerate. It's been easier to make multiple grade leaps in individual subjects, and it's allowed ds to stay in a grade with his peers where he is comfortable. Some kids want or don't mind jumping ahead of their age-peers, our ds was happy where he was socially.
One problem that you may run into with either full-grade or single-subject acceleration is that if your ds is placed in a classroom of typically-achieving students (instead of a rapidly-paced or indivually-paced classroom), he might still find that school is boring because it's slow - even if he's accelerated by several years. That has happened to our ds, but it's also something he doesn't really mind in the overall scheme of things because he likes his classmates and he likes his school.
Last thing I'll add - I have three children, each with different degrees of ability, and every single danged one of them, at 8 years old, told me recess and lunch were their very favorite parts of their school day. So did most of their friends, most of our many nieces and nephews, and most likely any random 8 year old we ran into at the park or anywhere on the planet. I don't doubt that your ds needs more challenge, but I wouldn't go to the school and use the preferring recess and lunch as signs he needs more challenge or as signs he's clearly bored. Chances are most of his classroom peers also prefer lunch and recess
Best wishes,
polarbear
ps - one thing about the low marks on paying attention and participation - my ds used to get remarks from his teachers about how he was staring off into space etc in early elementary, and I understand how his teachers thought he wasn't paying attention because of it (and to their credit, he was most likely daydreaming during part of that staring off into space!)... but I wonder about the participation marks - have the teachers said he isn't participating? Is that in not doing worksheets etc he finds boring, or does he not participate in group projects or class discussions etc? I'd want to know a bit more of the details on participation, because it's possible that if he did jump in and try to participate in class more he might find it less boring (one possibility)... or there may be a reason other than being bored that he's not participating and it might be helpful to know what's up. Lastly, if he's not participating only because he's bored, if he was my ds, I'd encourage him to try. Naturally you don't want him in a situation where he's bored stiff all the time, but that's our where our role as parents comes into play we advocate to get our kids more challenge. I still expect my kids to at least participate in class while they're there, even if it's not the ideal level of challenge.
