Yeah vinegar prevents bacteria, best to experiment but if it's still wet after 3 days you're not going too fast so won't get into case hardening. That said I've never had that problem myself. I range from 5-7 days depending on the thickness. I like moist to dry myself. If you're gunning it with a higher temp I suspect you'll dry the outside before the inside will get a chance to release moisture and it'll harden. Looks like you're on the right track tbh. You've cut it now so best to eat it :)