Ask the host to describe the physical separation in their own words: which room or annexe your dog sleeps in, what stands between it and any resident dog, and what happens at the front door when someone arrives. A host who has genuinely done this will answer in specifics, not reassurances.
Ask what happens on a bad day: your dog refusing food, barking for an hour, or reacting through a window. The answer tells you whether the host has handled a reactive dog before or is describing a well-behaved one.
Agree the medication protocol in writing (dose, timing, what to do if a dose is refused), fix update windows so you are not messaging all day, and do a short handover in a quiet place rather than on a busy street.