Sample struct helper function ignoring fleet with only some ghost entries

[k-doering-NOAA]

Thanks to @mkapur-noaa for reporting the following issue:

As an aside, our implementation of the helper function didn't get us there at first because we actually had two separate chunks in the .dat file for the same fleet (you can see this here); the first chunk is ghosted (all values are -7) so the helper ignored that fleet entirely, not picking up that there were indeed CAAL entries for that fleet later on (starting on line 792).