If you don't want to use a merchant account, you can use a deferred payment processing system in conjunction with your external point of sales (POS) system. Rezdy Vault is one example. It's not a payment gateway, but it provides a secure credit card validation and storage that can be used with your POS system.
In this case, the customer inputs data which you receive manually. Their data doesn't pass through a gateway, so you can inspect all orders and connect them. While automated credit card processing makes sense for tour operators who have a fixed availability and price, businesses with a high likelihood of cancellations due to weather - such as hot air ballooning or surfing - would be better off with deferred payment processing, which is only semi-automated.
The advantage here is there's no additional cost because Vault stores the customer data, and then you manually process it. You can avoid the hassle of charge-backs by waiting to charge the card until you're sure what to charge. If they don't show up for some reason, you can easily apply your cancellation fee.
Available with Starter plan and above.