You can try setting up a ACE (adwords campaign experiment) where you take your 'tried and true' exact/phrase match terms and then triple the bid.

See what happens to your ROI. https://support.google.com/adwords/editor/answer/1399246?hl=en

Honestly though, if the campaigns were running well and ROI only improved by cutting...you're projection is really an imaginative narrative.

Also - I'd try to find your cost per new customer, provided you're single channel and have a good working customer definition.

best,

Jeff