Just like I would be leery of letting a stranger ride with me I would be hesitant to ride in someones boat I dont know.
Some people seem very nice on the forums but drive insanely or
behave badly around large groups.
As for trades I would rather just cover some of their costs and make my own arrangements. Cover 1/4 to 1/2 (depending how many on boat) the fuel and entry fee for the person giving me the ride.
Just like when buy a boat and/or car maybe best thing would be to reference other members and ask for reccomendations on who would be a good match ?