Your wife needs to pack her own pack. That way she knows what she has and where it is- reduces anxiety. OK for you to double check it, but let her do it. She should carry all her clothes, personal hygiene stuff, sleeping bag, sleeping pad, water, trail food, cup, spoon and perhaps bowl. Although you both only need one first aid kit, she should carry items that she regularly uses, such as moleskin for fixing blisters, fire starter such as matches, and any medications such as allergy pills if that is used. If you are backpacking where bear cannisters are required, then all the food and smelly stuff needs to go inside and you should carry it. I think it is important that everyone learn to navigate, so if she had her own set of maps or GPS, then she could follow along and feel more oriented.

I think you need to just decide that you two will NOT ever get separated.

The most important thing is to buy her a light weight (with all the choice now I would not buy a pack that weighs more then 3 pounds) pack that fits her well. She has to be there to get fit. Do not just buy one on the internet. All pack suspension systems have a recommended maximum carrying load, which usually is over-stated. A "40-pound" load capacity usually means it will carry 30-35 pounds comfortably.

The recommended weight to carry is about a quarter of your ideal body weight. If you are 20 pounds overweight, that does not mean you can carry more weight! Quite the contrary, you already are lugging around 20 pounds! So, if a quarter of her ideal weight is 25 pounds, then get a pack that will comfortably carry that weight. There are expidition packs out there that will carry 70 pounds, but she does NOT need that!

You need to proportionally distribute both bulk and weight. Most women's packs have smaller volumes, so you probably need to carry more of the bulky stuff. In fact, if she were to carry the smaller but heavier group gear, her pack would be more ideally loaded. Heavy stuff goes adjacent to the back, lighter stuff near the back side. Be sure the weight is also centered side-to-side. Do not dangle stuff off the back of the pack, particularly heavy stuff. The only thing I ever put on the back of my pack is a foam sleeping pad, which weighs very little and can be tied on snugly.

The key to a light load is to only take what is necessary. For example, no need for an entire tube of toothpaste for a few day trip. Get those small travel size tubes. Keep food under 2 pounds per person per day. It depends on where you are going, but generally summer in the Rockies you need 2-3 light insulating layers on top, light long johns, and rainjacket (rain pants if in a wet climate). Stocking cap, 3 pair of wool socks, a hiking shirt, syntetic hiking pants. Get stuff that dries easily, NOT cotton or blue jeans. I take one of those 7-8 oz "puffer" jackets (bought mine at Target for $50) just to be warm when sitting around in the evening. No need for camp shoes, unless you plan to wade across a lot of streams.

I think there is a gear list somewhere in this forum.