Log files in Always on Disaster Recovery Situation
Is there any way I can handle it better than just letting the log files grow?

I believe you have the ideal options covered already. You either

Let the log files grow for the duration of the outage, or
Remove the replicas that are offline from the AG (and re-seed them when the primary datacenter is available)

I'd lean towards #1 if you have the disk space, and #2 if you become aware that there will be an extended outage (or disk space is low).