What I did, when I was on the PC, was make a fake trade. I would usually have a pet of slightly lower value or something that I didn't want anymore, so I'd "trade" it for the new pet. Then a few months later, I'd sell or trade off the pet I used for the fake trade, or I'd just keep it on the other account in case anyone was curious and asked me where I got my new UC from. I'd be like "yo, I traded with this pet with this dude".
But I had done this a few years ago... so not sure if that still works. All the pets had survived and I never got caught, but it appears they're all frozen now. Not sure why... but I still never got caught 0-
Personally, I wouldn't make any kind of board to draw attention to myself. A "back from hiatus" board results in people checking your account out, which is the opposite of what I'd want...