You can buy Rowell and Cripps for basically 800,000, which is the same as buying a so-called super premo and a rookie. Super premo goes at 120, rookie goes at 75 but is at risk of rests. You have locked in a minimum of 2 trades to upgrade the rookie. I would back Rowell and Cripps at full fitness to go at a minimum of 215 between them. No trades required unless you decide on a luxury one when it suits you (which the extra 5 trades helps), or they can be your last 2 positions upgraded if deemed necessary.
For Cripps and Rowell, 215 between them (so Cripps at 110, Rowell at 105), gives you 4730 over 22 rounds. Cripps/Rowell combination puts us behind by 190 points, but up by 2 trades, so it's a close call.
But I see this as the absolute best case scenario for these guys (anything higher is just wishful thinking). I'd prefer to make my decisions based on expected value, rather than best case value. Assuming they both improve on last season, Cripps could be anywhere between 100-110, so call it 105, and for Rowell 90-105 seems fair, so call it 97.5. That's 202.5 instead of 215 and gets you 4455 over 22 rounds - a deficit of 465.