Mailing address for nonconforming guest house?

[Nate Wiger]

Hi all, I'm considering buying a SFR with a guest house out back that is currently used by the owner's son. Owner and son moving out after sale. It's not an official ADU/JADU so due to San Diego rules, it doesn't qualify for its own address. I don't want to convert it to an ADU because I actually want to add an ADU + JADU for a total of 4 units, then rent all 4 out.

I've seen units around town that seem to be flying under the radar with addresses like "1/2" or "#A" which are not technically valid in this area of San Diego. It seems like the mail deliveryman learns that "#A" is the back unit and starts dropping off mail there.

Has anyone else run into this? I don't see a path to an official address (guest quarters are not eligible for separate addresses in SD) so looking for creative solutions. Thanks.