Re: Buy a truck or join a marina?
Keeping the boat in the marina will limit where you can boat and make do it yourself repairs and cleaning a hassle. Besides, money spent to keep the boat at the marina is money that could be spent on a truck, which in turn has other uses. If you like you gas mileage, buy a third vehicle, in most cases, with a good driving record, a third vehicle on you policy is minimal. I pay less than $300 per year to have a third vehicle on mine and I'm in NJ where insurance is insanely high.
If you can store the boat either indoors, inside a garage or under a cheap metal roof, you will add years to the life of the boat and it will no doubt make taking care of it far easier. Coming home late at night after a day on the water and having to flush the motor, clean the boat inside and out and secure a cover on it properly is a real hassle.
If storage at the marina is not covered, there's no way I'd go that route, unless you look at your boat as a short term investment and don't care if it gets sun or weather damaged. Most marinas around here just have open docks and dirt parking yards for boats not in the water. They also charge a fee to put the boat in and out of the water as needed too.
Keeping the boat in the water full time will also mean more boat maintenance as well, you will have to consider a good bottom paint, probably every season depending on the growth there, a trailered boat generally don't need any bottom paint.