There are options to try and get more rebounding without giving up Crowder. It sounds like Crowder is staying.
Room exception - sign Dedmon or Black.
Trade Mickey, Jackson, Nader, 2019 Pistons 2nd round pick for a backup PF. Two guys that match up salary wise are Kyle OQuinn and Noah Vonleh.
OQuinn has two years left. Getting him and someone with the room exception would give you two contracts making around $4.3 million that would be tradeable next summer too.
IT. Smart. Rozier
Hayward. Brown. (Veteran minimum guard)
Crowder. Tatum
Morris. OQuinn. Yabusele
Horford. Black. Theis. Zizic.
That's a huge lineup, but you could always go small when needed:
IT Rozier
Hayward. Smart
Crowder. Brown
Morris Tatum
Horford. OQuinn.