I struggle with the term "full fem", since I do not know where the line is. If it is the percentage of what you are wearing, was originally marketed to females, then many of my outfits are way over 50% and many close to the 100%, with my bush hat and nose ring, the only gender neutral thing on my body. As in this outfit.

If you are being picky, the one male thing here is the skirt, since I made it for me, adapted from a pattern with a picture of a woman on the front. But I know this and now so do you, but the person in the street just sees the skirt as part of the whole look.
I think my metric is one of "ME" and what I call my "Style". If I am happy with my look and in control and ready to rock the outfit, then the composition of female/male items is of no concern. If I am on the back foot, being attacked from all sides by my family, then black kilt, black DMs and Male Jacket will be the order of the day. (The fact that my tall black DMs come from the pink side of the DM shop, is just a comic fact that I keep to myself)
I think it is more of what is in our heads. As soon as you put on any skirt, there is a section of society that has you in the woman box anyway. When I first bought my Skirt Craft skirt, my male/fem meter in my brain was happy since I was rocking a gender neutral skirt, however Mrs mouse took one look and immediately put me right, "it just looks like any normal skirt, nothing special". So with that, I realised, a standard Roman denim skirt was just as OK for work as an expensive Skirt Craft was, since nobody was aware of the difference, just me and my brain.
I have had a similar journey on shoes/boots. My first real boots for my skirts were my tall Tinberlands, which are manly boots, made tall and sold to females. Same with my tall DMs and Converse. Makes no sense to me why a boot for a man can only extend to the ankle, except for riding boots and country boots, such as my Dubarry boots. So again, the metric has now changed to what shoes/boots fit my feet and I think look good, with the rest of my style.
I am now a free dressing man, I am not trying to look like a woman as many manly dressed women are not trying to look like a man. We are dressing as we please and in what suits what we are doing or where we are going.
Daily, a happy man in a skirt...