You might want to consider doing some tweaking on the standard plants. As it stands now, farming in Dwarf Fortress is ridiculously easy and profitable. Aboveground crops can grow year-round, as can underground plump helmets. You will also be able to harvest multiple times a season, even more so with the plump helmets. Not exactly what one might call "realistic".
There is a [GROWDUR:~] tag (can be seen on the plump helmet entry) that defines how long a plant must grow before it can be harvested. There's an archived page on the wiki that has information on what the particular GROWDUR values are, but it's a bit late in the evening for me right now and I've got my own projects to attend to.
That tag will let you tweak certain plants so that they require three seasons of growth before they can be harvested (plant in spring, grow through summer, harvest in fall). Also note the [SPRING][SUMMER][AUTUMN][WINTER] tags, which determine the seasons a plant can grow in. If it has all of them, it can grow year-round (note: I believe it is possible to make plants require multiple years of growth. But I've never tried it for myself, so I don't know).
Quick question though... How exactly did your hunter die? It was obviously some strain of the dreaded Tarditas virus (often fatal, and believed to be hereditary), but I was wondering if it was more closely related to the piscis or the insilio strains.
In other words, was your hunter eaten by a fish or did he just dodge into the river when a groundhog nibbled his foot?