Gray tank neck crack (is patching possible? Plasti-Mend?))

Am stuck in Apache Junction after a cracked gray water tank replacement on my 2014 Excel Winslow 31 IKE went awry. Unbelievably, they dropped the new tank on a cement floor while carrying it to the rig, causing a small separation (about an inch wide) right at the neck/tank juncture. The experienced RV tech insists that there’s no reliable way to repair it, meaning I’ll have to wait 7-10 days for another tank.
I’ve read some prior posts from those who have successfully patched cracks. Is the location of mine located at too vulnerable a place subject to high stress? Thanks,
David