I also wear size large and have all my Sitka Gear clothing in that size, except for one of three Celcius vests that is an XL (the other two are large) for times I am somewhat bulked up and want another outside layer on my body. I don't use the XL much, but got it for that rare occasion.
I agree with Steve's suggested minimal outfit, except I would add a Celcius vest and would substitute the Kelvin jacket for the Kelvin vest because of the extra warmth and versatility of the jacket. I also like the zip tops for the Core and Traverse underwear better than the crew tops because of the extra neck protection when needed. In addition, I prefer the Jetstream hat because in has a short bill which helps keep the sun, rain and snow off my face. I don't have the Kelvin pants, but if you want to be able to assure warmth in cold weather while sitting on a stand, they would certainly be a welcome addition and would pack down to nearly nothing. I will probably end up getting a pair for myself.
My suggestions are not better than Steve's, and may not be as good for most people, but they are what seems to work best for me. The main thing Steve's suggested outfit gives up is a little extra warmth if someone tends to get colder when hunting. I like the additional comfort zone and don't feel like the insulated sleeves really interfere much with my movement. I do have the Kelvin vest, and it is better than the jacket for some conditions; however, if I could only have one or the other rather than being able to have both like I do, I would pick the jacket. I also use the jacket as filling for the pillow pouch in my sleeping bag when sleeping out, and it is very comfortable under my head. The Kelvin clothing pieces are some of the least expensive in the Sitka Gear line and provide much greater warmth than most of the other pieces are designed to give. There are other PrimaLoft insulated alternatives, such as the North Face Redpoint jacket (which I use as an excellent cold weather daily wear and travel jacket), but the Redpoint is not as fitted or as light as the Sitka Gear Kelvin jacket and costs about the same. If you already have a PrimaLoft jacket like the Redpoint, you might want to try it with the other Sitka Gear before laying out the money for the Kelvin jacket or vest. My Redpoint actually works pretty well under my 90% and Celcius jackets, but it does not have the micro-fleece lining around the inside of the neck for comfort and noise reduction. If you use the zip-T neck Core and Traverse tops, they will do a good job of adding most of the advantages of the micro-fleece neck lining that is missing in the Redpoint. All that said, if you can afford the Kelvin jacket or vest, they will work better for bow hunting.
The one major complaint that I have heard about Sitka Gear from guides and hunters is that it is not as quiet as fleece and wool in close quarters bow hunting. I have to agree with that complaint, but even a little wind or background noise will hide the small amount of fabric noise made by the soft shell outer layers of the Sitka Gear. When the wind is absolutely still and the woods are dead quiet, I have found that deer can hear me as I move (like drawing my bow) in my Sitka gear. I think it is about the same level of noise that is made by Windblocker fleece, which isn't much but can be noticeable under the right conditions.
Allan