Fullsix do a set of swingarm covers that include the chain guard as part of the side piece. Dont know if it meets acu regs, but worth a look. You will also get premier member discount from conquest carbon if you deal with them.
You can use either a chain guard incorporated into a carbon fire swingarm cover, or one that is fitted by tapping the swingarm. You shouldn't have any issues with ACU regulations or scrutineering. The ACU and MCRCB regulations both state that a chain guard must be fitted, but not how it is to be secured.