I can see a few possibilities:
1. Animate in two separate passes (letters in one pass and objects in another pass) and composite the results together (depending on how the text and objects interact, you may not be able to do this).
2. Use ProAnimator, which can have an unlimited number of tracks (and offers tools to animate a bunch of objects quickly. This will cost your money if you don't already own it, of course. You can animate in ProAnimator and then import the rendered results into AE.
Maybe other users have dealt with this issue in more clever ways.