Ignoring costs and whether or not you can turn a profit, I like option C. Basing on equipment gives them choice based on their budget. Around here, renting a boat was so expensive for a basic fishing boat I gave up and just bought a boat. Heck, for the price of a daily rental once a month I could buy a new boat and pay less on loan payments...
Making it cheaper to rent for a day, even 8hrs as a full day, then to rent for 8hrs at hourly is nice. Some places just do the math for you with the daily rate. $50/hour for 8 hours = $400 daily fee. Some dropped it to $350/day, not much of a bargain. "Rent for 7 hours, get an hour free!" Knocking two hours worth off is a better deal.
Now allowing a 24 hour rental? I would LOVE to see that. I would love to rent in the afternoon, fish through dusk, then wake up and be able to go back out at dawn and not have to wait for the rental office to open. Being able to use it on your own schedule for a full day or even a full weekend would be awesome. There are places near me that rent pontoons like that and will haul to a lake of your choice within X miles, but few that rent fishing boats the same way.
As long as you can turn a profit doing it, or are running a campground and want to just break even on it so you can use list it as an amenity to attract customers ("Cheap fishing boat rentals! Newer boats, with different options based on your budget!"), then go for it. Make it affordable or severely undercut competitors, and you will probably end up with a waiting list. Oh, and have a waiting list. Nothing is worse for customers than the stress of trying to call everyday to see if one opened up, just to find out they missed it by five minutes.