I may be completely misunderstanding, so only take from this what suits you, if anything. I wouldn’t use a peg system but memory palaces. I am learning French and Chinese - I use memory palaces for both, but in very different structures. French is closer, so I’ll talk about that.
I use rooms as palaces just putting everything that is there in the room. The bedroom, bathroom, kitchen, living room, garden and the streets I walk to the shops and the things in the shops. It doesn’t matter that the vocabulary overlaps other things I have in those palaces. My brain has no trouble just extracting what it wants. I use the fruit shop and supermarkets for products - in gender zones as suggested by Dominic O’Brien. Feminine fruit and veg in the fruit shop, masculine in the supermarket along with all masculine products. Other feminine stuff in another supermarket. I use my body for body things.
I have another memory palace for adjectives and another for adverbs and I do those in alphabetical order. Then I have memory palaces for verbs, keeping the different types of verbs (regular -er for example) in different palaces.
I don’t set up the palaces with the locations in them. I chose real spaces and then add locations as suits me. So I use very big spaces, mostly on walks I do around town. Health and French at the same time!
Plus I use characters. I have a female and a male toy bear who I associate with masculine or feminine objects which aren’t in the gender zones, such as in the rooms of the house. You could use any male and female character and add in a third for neuter.
Hope something there might be of interest.