If you want to do this, then do it. There will always be problems and issues and tigers to be aware of. I think this is a good idea. Follow your bliss.
Bellys and skirting 9-10oz, are good for corsets. Belly’s will stretch a bit. Put skirting where you want firm support.
Personally I think 2-3oz or 3-4 oz at the most for wallets. Thin but stiffish. Wallet liners, mission grain, glazed pig liner or another 1-2oz piece to give firmness for card pockets and bill pockets.
Oil tanned utility sides, 5-6 oz worked very well for a tricorn hat. Sewed like a dream.
2-3oz sheep skin veggie tan made a nice flat cap, although I would have gone for a more malleable, less stiff hide if I had known then what I know now. The seams show the stitching in some places.
‘Don’t use variegated thread, no matter how much it calls to you, unless you are willing for people to see it peeking out of spread seams.
Garment weight lambskin makes lovely warm hats and mittens. I’m not brave enough yet to do gloves. Soon.
‘For belts I like 6-8oz, because I haven’t seen two smaller thickness’ together yet.
Gum tragicanth is a lovely sealer, easy enough to use, just be sure to press hard enough with your burnisher, or it will come out cracked and patchy instead of smooth and soft. Use it after you dye or stain. It is a resist. It stops dye from soaking in.
Buff after dye or stain. Buff, buff, buff. Then buff some more. Because if your buffing cloth isn’t clean, you’ll buff the excess dye off with you’re silk blouse, or white jeans, or couch.
I hope this helps. And remember, it’s mostly personal opinion, no one is in charge of your project except YOU.