Re: do i have to have foam
Foam is for safety only. Fiberglass boats by themselves, if swamped, barely float, so the builders ad floatation foam to keep the boat and the Outboard and the batteries and the people floating.
your wooden boat have better floatation already than a fiberglass boat. and yes there is a trade off between foam WILL hold water and make wood rot faster, vs extra floatation if there is an accident.
also to throw in here is that foam up under the gunwhales and the bow, is sometime better, because it helps to keep a swamped boat floating upright instead of upside down. And foam under the gunwhales and bow, is less likely to get wet.
Do some searches, there are 1000's of post in the forum on foam. You'll get tired of reading the posts.