Sissy girls shouldn't have any body hair, so remove all the hair on his body and enforce that he's constantly smooth.
Enforce that he is completely shaved smooth every day all over his body and do random inspections. You should tell him that real men have hair, and he's not a real man obviously. Since he acts like a sissy and should be treated like a girl, you don't want to see him with any hair on his body, and you want his skin silky smooth (no stubble). Tell him you will not tolerate finding any hair, and if you do you will make him pull each one out one by one, or send him to get waxed at a salon.
Shortly after you lock him up in chastity you should have him strip naked and get in the shower. Then hand him a razor and give him the rules. You should have him shave every part of his body from neck to his toes, so that he has no hair on his legs, arms, chest, or back. It can always grow back if you want it to, but you are giving him a very strong message by insisting he's as smooth as a girl.
When he's finished make sure to re-enforce how much of a sissy girl he looks like without hair on his body.
Teach him to keep himself smooth and soft with lotions and creams as well. Conduct regular inspections and enforce punishment if you discover that his hair grows so that you can feel it prickly. If he can't keep his body smooth, simply punish him boy forcing to get it waxed...which will serve as an uncomfortable reminder for him to keep better control of this.
This will remind him on a daily basis that he's being feminized by you, every time he steps in and out of the shower, sees himself naked, or his silky skin rubs up against his clothes.
Besides being very hygienic and extremely sensual, being forced to maintaining a smooth, hairless body is constant reminder of your encouragement of his sissyness. You both enjoy this.
You should enforce this at least once every 2-3 days, and always whenever you feel or see a hair on his body below his neckline.
Don't get afraid… his hair can always grow back. Also, many athletes like swimmers and cyclists have completely removed the hair on their bodies. It's also a fashionable trend among men who are into fashion and keeping care of their body.
The worst thing you can do is support hairy legs or arms on your sissy girl when he's bound to be feminized. Just don’t allow it, Period!reminder of your encouragement of his sissyness. You both enjoy this.