NHawk,
My first thought is that perhaps you could volunteer to be an ADL for the second Webelos den. Then you could lend your experience to the DL without as much of a time commitment.
And as for the Webelos rank, most activities are supposed to be done with the Den, not at home. Parents can't sign off on activities like they can in earlier ranks. There are a few activities that are to be done at home, and then the Cub is to discuss it at the den meeting. So, if all the Cubs are going to all the meetings, and doing all of the activities together, he shouldn't have to wait for anyone. If the other Cubs are missing meetings and that's why he has to wait, that's just wrong.
IMHO,
Shane