You can bet chunks, I suggest you do.... on longshots and parlays. Calculating the rollover is tough , the way BP does it, if you already have a cash balance. I suggest doing it all one day or weekend ( multiple bets, if desired), then you'll have some kind of figure to work with on the rollover.
It will be very complicated if you use the FP over many weeks, with a cash balance already there. I wouldn't want to have to figure that out.
dont think this is very sound advice, the odds of getting the best available line all in one day, all at one sportsbook is slim to none, if you are not in a rush, you should play it soundly and with care, while shopping for the best available line, dont be desperate just to get it rolled over.
as far as calculating the rollover, well, you dont really have to because you can ask customer service to do it for you at any time, besides, is it your intention to ask for a withdrawal the second the rollover is completed to the dollar? without risking a penny more? I know some people play like this, personally, I usually give the sportsbook a little more as a good will gesture as I dont want to be seen as "that guy".
One thing I do suggest is to keep print outs of your transaction history depending on how long the transaction history at the particular book goes back, for example at
Betjamaica the "account statement" only goes back 14 days, so if you print it once every 14 days you will have a permanent record, this of course will allow you to verify any rollovers that are calculated by customer service.