First off I’m so sorry about your loss. I lost my beloved dog a month ago and it feels like yesterday. I can’t comment on what stage of decomposition the dog will be in but I will say expect to be weirded out some... in regards to cremation you can call your local vet or emergency vet and see if they will take him and do the cremation process for you. Unfortunately we had to take my dog in under traumatic situations and the staff was so great and handled the cremation plans. It actually didn’t cost that much. We paid extra for a special urn for him but you typically get a nice cedar one. I will say having him home feels good. I can look at his urn when I want and even talk to him sometimes.

Kinda strayed away from your question but I hope it helps. If digging him back up doesn’t sit right with you could you go visit him at your friends place when you wanted?