Instead of booking a rental car, you could consider using Cal's Taxi Service. Here is an estimate of fees:

From Halifax Airport to Bull Point Estates Southwest Port Mouton for six people via Hammonds Plains Rd costs

$345.00 credit card

$340.00 debit or save and pay

$335.00 cash/e-transfer

There is more information on his website!

The wedding venue is a 2 hour drive from the airport

There is a car ferry that runs between Bar Harbor, Maine and Yarmouth, Nova Scotia.

Yarmouth is close to the wedding venue and a wonderful entry point to Nova Scotia. Bar Harbor is next to Acadia National Park!

2024 Rates: 400 USD round trip for a car and 230 USD per person. It is expensive but convenient!