What do you recommend? Trunk Battery, like to put a inline fuse. what size?

No they do not. Its a lever (small and red) that has to be manually moved 90 degrees to reset.
That's a lot of amperage to "pop" it. So if there was a major short, you will be glad it did not do it automatically.
On a truck lift gate they pull up to 350 amps with a single starter type drive motor.
I went there today and they said they only have 200 amp circuit breaker that you can reset. Bummer