Post pics of the boat interior with dimensions and maybe we could give you a cou[le ideas. I would also HIGHLY recommend you just take it to a profesional and have it done.
You could have a fairly basic install done for less than $500 and you will have the piece of mind knowing it wasd done right.
Myprice is an off the top of my head guesstimate and could be much less or much more once they look at it.