I've modified my installation a bit based on feedback I received here and elsewhere.
I'll be staying with a 5 amp circuit, but changing from a slow blow to a standard inline Anchor fuse for exactly the reason that Bill mentioned -- the breaker will be slower to trip and I want to protect the TV.
I'll keep the breaker at the 12v outlet so I can turn off power to the outlet for troubleshooting or if I need to conserve power.
When I get to the boat this weekend I'm going to check my breaker panel and determine if Catalina installed a hot bus (always hot regardless of battery switch position). If not I'll add one as this will be a cleaner installation than tying multiple lines to a battery terminal.
I should be OK with the current draw from the spotlight. It's a standard West Marine light with a 12v plug that was previously used on a 5 amp circuit.
95 Catalina 30 Island Time
“The sail, the play of its pulse so like our own lives: so thin and yet so full of life, so noiseless when it labors hardest, so noisy and impatient when least effective." - Henry David Thoreau