If we steal pick 12 for Cameron (he is nowhere near worth that), this will make up for paying overs for Gibbs. You simply cannot win on every deal, especially when trying to pull a 2-year-contracted player from another club. It's about the sum result of a trade period, not just one trade (unless you only do one, of course).
If our trade period is-:
Out - Lever, Cameron, Pick 16 (Gibbs trade), 2018 R3 (Lever trade)
In - Gibbs, Pick 12 (Cameron trade), 2018 R1 (Lever trade), 2018 R2 (Gibbs trade), 2018 R4 (Lever trade)
Then, that is absolutely fine.
Negated - Pick 10 in for Lever, out for Gibbs.
p.s. Charlie Cameron interview coming up on Trade Radio.