Modern Vespa

As I opined earlier above - a 50A fuse should be OK for this situation.

You were installing something.

This will be an installed and tested situation - with someone monitoring what's going on as well.

Perhaps though, as the OP had to ask, they should just prepare to use the provided jump cables and alligator clips in the unlikely event the booster would actually ever be needed.

The pigtail coming off the battery for the trickle charger has a fuse in it so should be good if in an emergency need to jump start the battery.

I think that charging pigtail w/7-1/2 amp fuse would blow immediately if it was used for jump starting.

Which is why it should be substituted. 50A or dead short.

I don't know but I think I had once a battery that went dead in normal use.
It was on my car, the car I then used daily.

One morning I stepped into the car, and noticed the interior lighting was a bit dim, switched on the ignition and when I turned the key to start the engine, everything dead. I never noticed anything unusual before.

I bet if you read the voltage it'd have been 8-10V - so not dead as such! A completely dead battery reads less than 8V, and any load sends that down to zero. Nothing will revive such a battery, not even the deep de-sulphation cycles of a good motorcycle battery charger.

Normal use won't kill a battery that far - it will have been left fully discharged for a long time.