I don't know if this is technically feasible, but here's the rough idea:
Every round, five random delegates are temporarily dropped and substituted with five random candidates from the top (say) 1000, for the duration of the round.
The next round they're of course reinstated, the temporary five are dropped back to standby and there's another draw.
This way the 101 "real" delegates are still signing 95% of blocks, while everyone in the next 900 has a chance to sign a block every couple of days.
This has several worthwhile effects:
1) allows standby delegates to prove themselves to potential voters
2) shuts up the anti-bts argument that we "only" have 100 validating nodes. Now we have a thousand! (for a price of 101)
3) allows more people to participate and invest themselves emotionally into the project
4) gives more weight to smaller stakes; incentivises voter participation
5) makes the theoretical 51 delegate attack slightly harder (attacker now needs to compromise 56 delegates)
6) makes a DOS attack an order of magnitude harder