came here to post the same thing .. our town is apparently collecting all the boats/vehicles, and since they don't decay, they don't spawn anywhere else.
would be really useful to have a novehiclespawn flag which included boats, modular vehicles, and hot air balloons

That, HABs, and ridablehorses would be great

If you are interested i have a version that can do it. Only boats will spawn in the circle though, im HardStyle#0001 in discord, just DM me to get it