Either a leaf-loader or a ZTR with bagger will save time. Both will chop up the leaves quite a lot, which will allow for fewer dump runs. Try the gator blades.
But the big issue is that if you are not charging for dump runs then you are not charging for your time on the job. If 2 men are taking 4 hours per cleanup and only charging $80, then you are billing at $10 per hr/per guy for what should be one of the most profitable services of the year. Pay for gas and equipment and you may be in the $7.50 range. Heaven forbid you have one equipment failure, you are losing money. Every market is different, but around here 4 hours for 2 guys would be in the $400 range.
I don't want to sound negative, but you may not have the right equipment to be competitive until you get a ztr or leaf-loader.