Number of rerolls with column tactics

By Xquer, in Runewars Rules Questions

If I am running the 1x3 of leonx riders with column tactics, do I get one reroll since I have one tray or none?

Column tactics:

" Your number of ranks for rerolls is equal to the number of trays in your front rank."

From the rules 10.4:

"Step 4—Reroll For Extra Ranks: The attacker rerolls dice
based on the number of full and partial ranks he has behind
his front rank.
• If the attacker has a full rank behind his front rank, he
can choose and reroll any number of his dice. A unit can
perform this reroll one time for each full rank it has behind
its front rank."

Not clear on how to do this counting:

1) Do I need another tray to get the reroll so I have "an additional" rank?

Or

2) do I count each tray as a rank that itself provides a reroll?

For the record, I have played it as the second.

If you have a 1x3 you can change to triple threat no reroll. It's the same as a single rank unit at that point. The 2x3 will get one full reroll, even if it's missing a full tray from the back it still gets full threat and reroll due to the way column tactics is worded, which is what makes it so good.

think of it as in order to roll dice you use the first rank, then to roll the dice again you must use the next rank, if there isn't one then no reroll.