I am thinking something like this, if I may:
I am throwing this together pretty quick, maybe it can help!
1,500 chips x 60 players = 90,000 (not including rebuy/addons)
Also, I would not add-on chips after the 5th round, this adds more chips to the total and may not thin the field as quickly. Personally, I would advise against it. Rebuy/addon UP TO Round 5 would be fine, given the low chip count and structure.
if lowest chip is $25 (if lowest is $5 chip, then maybe start with 5-10, 10-20, then go to 25-50)
25-50
50-100 20 minute blinds
100-200
break - 10 minutes
150-300
200-400 20 minute blinds
300-600
break - 10 minutes
400-800
500-1000 20 minute blinds
600-1200
break - 10 minutes
800-1600 ante 50
1000-2000 ante 100 blinds are now 15 minutes
2000-4000 ante 200
3000-6000 ante 300
break - 10 minutes
FINAL HOUR - 10 minute blinds
4000-8000 ante 500
5000-10000 ante 1000
6000-12000 ante 2000
10000-20000 ante 4000
In any league/home game I have played in that has a time limit, the final hour goes by fast to:
1. narrow the field
2. end the game on time
3. promote aggressive play