Making a multicart that emulators will recognize (Paid?)

Say I wanted to make a multicart of two 24 Mbit (3 MiB) HiROM games, and I wanted to test the menu that I'm developing in an emulator before I commit to building the hardware. I'd need probably some sort of latch outputting on A22, analogous to what BNROM has. Do any well-known emulators support anything similar to this? And if so, how is the presence of this latch reflected to the emulator?

The last few times I made multicart menus on NES, I was able to handle all the work myself because I was piggybacking on existing discrete mappers or low-end ASICs. These included Forbidden Four on MMC1, Midwest Gaming Classic 2011 on UNROM (Crazy Climber version), and Action 53 originally on BNROM. But it might be a bit harder on Super NES because nothing really used mappers outside coprocessor games.

I might even willing to pay someone to put support for this into Mesen-S or bsnes-plus.

I wrote a multicart system without testing the multicart part in emulation. It's not like it's doing interbank calls; if anything's broken it'll be very obvious from the outset.

I could do the job for bsnes-plus, but I won't be free until 2-3 weeks later. Perhaps others will be available sooner.

Multicart need a mmc, I think it's easy to support in emulator,but not support now,
because it's the homebrew mmc.

I have made a 2Gbit multicart.emulator only support show menu(if no homebrew mmc inculde in emulator).