1) Decide how many arrows you think you will need and then multiply by a factor of 4. If deep snow is encountered most shots will result in lost arrows. Dean will most likely retrieve a 10 year supply of arrows come spring thaw and we should consider this his payment for sponsoring the event.
2) In case of "cool" temperatures requiring bulky clothing, a light bow easily shot should be included.
3) Some form of briar resistant pants (no such thing as briar proof). Carhart type in pants, bibs, or coveralls although some find coveralls to be somewhat restrictive to archery shooting.
4) Socks, socks, socks. Treat socks in same manner as arrows. You can't have too many.
5) 2 pair of insulated, rubber bottom boots or one pair of rubber bottom boots with removalable wool liners w/extra liners. Wet, cold feet will ruin your day quicker than anything.
6) At least 2 pair of gloves. One to wear, one to be drying.
7) Set of gaiters. No need for the fancy polarfleece or wool ones, nylon or Gortex work well and are relatively inexpensive. Great for keeping pants dry in wet snow.
8) If present snow conditions persist, set of bearpaw or Michigan style snowshoes will come in handy. Busting trail through frozen snow of more than 6" is tough on aging men.
9) Wool or acrylic stocking cap that pulls down as face mask or, if you do not mind looking dorky like myself (Tom(Longbo) speaking here), a wool cap with ear flaps.
10) A pair of sunglasses for those anticipated bright days with snow covered ground.
11) For those tenting, a shovel may be of use in clearing a campsite in the snow. This item may also be of some use around the evening campfire, as well as a good set of hip waders:-).
12) Those staying in tents should provide some form of pad to keep between ground and sleeping bag. Thermarests or closed cell foam.
13) Pre-moistened handy wipes come in handy for personal hygiene. A few sealed in a ziplock bag placed inside a larger ziplock bag containing a days supply of toilet paper will be helpful. Will be tough finding useable leaves in January, even in "balmy" Ohio. Also usefull in cleansing hands after field dressing your rabbits if by some chance snow is absent. Yeah, right.
14) Again, for those who are tenting. It may be wise to make friends with, or, at the very least, not antagonize anyone with a rented motel room.
15) A lawn chair or stool, something to keep oneself off ground during possibly wet balmy weather. For those driving, if possible throw in an extra chair or two to help out those flying in.