I am having an issue at what looks like when Multisite starts to write Data into the new tables. I am using a different database than the master site, but I will be creating other new sites in that client db with new table prefixes. The install process looks to start just fine, then errors out when it tries to write data to the db. I have double and triple checked the db username and password and made sure the users have sufficient permissions assigned. My site is hosted so the only access I have to settings is through my cpanel. It seems to be a permissions issue but I can't rule out a timout issue.

Any ideas?

When replicating website from one DB to another one, you have to provide the same DB user or setup the "multisites.cfg.php" file with the MySQL root user.

Probably the error message that you have is that you can not connect to the other DB.
In cPanel, you can assign several MySQL user to a same DB.