gottafish
I think you are worrying too much about the vehicle - I'd just try it out and see how it works, and then make your decision on that. This is fishing we are talking about... screw the van, get your priorities straight

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If you want a 22 ft boat & will not put a little extra weight on that van, the only solution I see is going aluminum. Check out the aluminum brands - lots out there, most popular in my area has got to be starcraft.. Aluminum hulls are the lightest boats available for thier size. The islanders have a closed bow / raised cabin and are at least as seaworthy as any 22 ft glass boat. Unfortunatly the hulls are not built with performance in mind and they don't ride as nicely. I don't think I've ever seen a walkaround, but there are pleanty of walk-through's & CC's out there.
Jon