So, my first shore dives using Toucan (at the Plaza) I pulled up to the dive shop with my trusty little pickemup and started loading tanks. I started to get nervous when I hit six, but we were planning a number of dives that day and didn't want to return before night set in.
A couple of the DM's walked by as we were loading tanks and no one batted an eye. I thought we were in for a hassle when one of them asked where we were planning on diving, but we answered truthfully and their response was "kewl." One even suggested laying a wet towel over the pile to keep them cooled down.
As far as I know, most of the operations will let you take as many tanks as you need. If you're planning a day of five dives for two people, the only requirement is that you have a big enough truck.
Then again, if you're not sure, why not call or email before you commit and ask?