If there are other larger farms nearby maybe you could talk a farmer into harvesting your field in exchange for giving you 100 lbs of dehulled oats. From what little research I've done I think 5 acres of oats would likely yield 60-100 bushels per acre and a bushel weighs around 40 lbs. So the farmer could harvest 12,000-20,000 lbs of oats. I'm not sure if the planting density is different for straw production vs oat production. And those numbers are for US production (not sure where in the world you are).
I believe a combine does not de-hull the oats. Oats still in the hull are a pain to turn into groats (edible oat seeds). So if the combine turns out de-hulled oats, you'd be all set. If it doesn't, maybe you can give the farmer the oats in exchange for money or other perks later (help with earth works, manure, etc).
If there aren't any farmers around, you could just cut the oats before they become viable seeds and leave the oat straw on the field as mulch for your forest. The oat beds I used as a cover crop last year made really good mulch this year.
I agree that the two of you probably can't eat all of those oats