IDA Processor Module: How to maintain register values if instruction doesn't modify them directly (ex. STATUS register, FLAGS, etc.)?

Question

I'm developing a processor module for a specific microcontroller. There are cases, when instruction modifies some register (lets call it STATUS) indirectly. By indirectly, I mean, that STATUS is not one of the operands for this instruction. As an example, let's take rlc instruction:

rlc A

It basically rotates A left with Carry (C). C is part of STATUS register (just one bit). I cannot modify anything within the ev_ana_insn callback as per IDA Pro documentation, so it looks like that:

def ev_ana_insn(self, insn):
    if b == 0x67:  # rlc
        insn.size = 1
        insn.itype = self.itype_rlc
        insn.Op1.type = ida_ua.o_reg
        insn.Op1.reg = self.ireg_A

That's fine. But in ev_emu_insn I don't understand how and where should I modify the STATUS register, since it is missing (and shouldn't be there in the first place) from insn.

I had a couple of thoughts, but they are not good enough in my opinion:

1. Use auxprefs in insn or specvals in Op1 and save the information about needed changes to the STATUS register. But still, I need to make these changes and track them somewhere during the analysis and emulation stages.
2. Map the STATUS register to RAM segment and modify it there. Here as example of such an implementation: https://github.com/Treeki/TM155-tools/blob/master/ida-module/ht68fb560.py#L470, but I don't know if it's the correct approach.
3. Put another Op2 in my insn, assign it to the STATUS register and modify it during the emulation stage. However, this approach breaks the whole disassembler, since it expects 2 operands, but really there is only 1. I can play around with that during the output stage, but I don't think that it is a correct approach and is more like a hack.

So, any input is much appreciated.