I have read (somewhere) that a prior interruption of the battery connection can be a cause of emissions testing failure. Therefore I suggest:

a) leaving the battery connected continuously from the protracted driving exercise until the inspection.

b) leaving the trickle charger connected to the connected battery when the car is parked for more than one hour.

c) no reason for not leaving the trickle charger connected to the connected battery all the while you are off Island. I would place the trickle charger under the hood to protect it from rain. Then, on your return, the car wouold be ready for inspection.

d) My hysterical imagination leads me to suggest that when the trickle charger is connected to the battery, the car be parked sufficiently remote from the house so as to prevent a fire in the car from endangering the house.