The README says you can still use the Expert mode switch, and buffer up to 200,000 workunits.
".....a ini-setting [rc564]/expertmode...this option is set to 1, the proxy will obey your settings of maxkeysready and minkeysready."
So right under [rc564] put expertmode=1
The pproxy will flush/fetch when the maxkeysdone= limit is reached, or the minkeysready= is below the threshold limit.
Set the minkeysready to something low, so it doesn't cause a signal for more units.
If you change the maxkeysdone to the same as maxkeysready, it shoudn't flush untill it's reached the minkeyready limit, or it's totally out of workunits.
The network is pretty fast, chances are you won't have a problem. but you might end up with a random or two, if a client happens to try and connect at that exact time the pproxy is out of workunits.