Not only is life too short to skin, the skin also contains some essential fat. I never buy skinless meat when I have the option to get it with skin on. Otherwise you need to find another fat source - lamb breast is great if your cat eats lamb.
Anyhow, here is a potential "easy" recipe
1000g lamb meat ------------------------------------or any other meat, beef, chicken with skin, duck, rabbit, venison
500g lamb breast (together that is 50% meat)
250g lamb heart (8.3%)
250g lamb kidney (8.3%)
1000g chicken wings with bones and skin (33.3% but remember this also includes meat)
98g ox liver, or 85g chicken liver or 300g lambs liver (you need more lambs or calf liver than ox or chicken liver to get the same amount of Vit A)
17g salmon (for Vit D3)
Supplements
seaweed powder 4.4g (for iodine amongst other things but also helps with metabolism)
brewers yeast 6g (for Vit Bs and other trace elements)
Vit e drops 6 or 50g wheat germ oil (very expensive in this country) for Vit E
Salt 1.4g to substitute for the sodium loss not feeding blood
Water about 1l (this is to substitute for the loss of blood and therefore loss of moisture)
This gives you
96% energy
94% calcium
103% phosphorus
44% iron
100% iodine (seaweed)
100% Vit A
99.6% Vit D3
93% Vit E
So the calcium is lower then the phosphorus but if you added 2gs of eggshell powder to this, the ca/ph ratio would be perfectly balanced.
The iron is a little low at 44% but if you managed to get your hands on some pigs lung and substituted 50g of the kidney with lung then that brings it up to good levels. Or get your hands on some fortain. Essentially, cats would be getting this level of iron from the blood of their prey (as well as some organs such as liver) but the meat we use in this cobbled together approach has been hung and drained.
Anyhow, that is what my calculator throws up for a bone-in recipe.
Other people do it differently, perhaps they will post here too. Well, and let's not forget if you go to rawcat they will just shout you down for using supplements in the first place. They have a confidence in their supermarket meat and cobbled-together approach that I don't have. So, I choose to use them.
Each to their own I say. There isn't just one way but this is my wayyyyyyyyyyyyyyyyyyyyyyyyyyyy