I'd be glad to help!

We did RTR last year and LOVED it. I did a post virtually every week with pictures on the Weekly Check-In that may be fun reading if that would be helpful, and there is also a photobook with pictures and comments dedicated just to RTR. Here are some links for those...
A few Weekly Check-Ins...
viewtopic.php?f=14&t=8686&p=63522
viewtopic.php?f=14&t=8525&p=62319
viewtopic.php?f=14&t=8358&p=60967
RTR's Photobook...
http://heartofdakotasphotobooks.shutterfly.com/33
I don't think the reading will be too much at all, but to make sure, have you used the placement chart to accurately place your ds? If so, and he fits well into RTR, then it will not be too much - it will be a delight!

As far as the extension package, there is a schedule in the Appendix that matches each day of the plans, and there are suggested follow-ups to rotate through (i.e. detailed oral narration, summary oral narration, summary of the reading, written narration with an opinion). Each follow-up has a clear paragraph to explain it further. Some families enjoy using the schedule and follow-up activities, some just use the schedule and a few follow-ups each week, some just use the schedule and no follow-ups each week, and some just have their dc leisurely read the books. It is very flexible!

I think it is more important for dc to do the core of the guide well, and then add the extensions if necessary, than it is to do a mediocre job on the core of the guide, and do all of the extensions and their follow-ups. I hope that makes sense!

There is much to love about RTR... the books are fantastic, the history Student Notebook is beautiful, the Shakespeare study was great fun, the art appreciation and artwork included were lovely, the science was hands-on and full of excellent skills, the Bible Quiet TIme was so fitting (we LOVED "Boyhood and Beyond" especially), and I could go on and on. I think it's safe to say you and your ds will enjoy it. HTH!
In Christ,
Julie