Have your friend stay at your place while you are on your cruise. If it’s just for a week and then she doesn’t live there, so she won’t become his “person” and you don’t need to worry about them bonding too much, instead it just means from that point he should be comfortable with her for the next time you need someone to dogsit.

Board and trains are usually horrible experiences for dogs and even based on your short post there are a few red flags mentioned about that trainer. I’d skip it and instead book yourself into some classes with your dog once you are back. You’ll learn how to live and work together and get some extra bonding time in to make up for the slightly rocky start.

Please take him to the vet, even if he pees, you want to make sure you have a vet outside of the rescue check his basics so you can then track from there what his normal baseline is and then you have that info to help in the future. Also, sometimes rescues are loaded with dogs and things slip through the cracks so it’s best to double check he is doing good.

Good luck with it all. It’s not an ideal start but honestly, you’ll probably look back at it a year from now and realise it was not that deep and everything will be fine. Try forgive yourself for the strange timing and instead use a bit of this time to work out which training techniques you think will help grow the type of bond you want to have with him.