OP I get that you're not concerned with whether these people are safe, but I still echo everyone else: for me, 3 months is not long enough *at all* to know someone who you only see on playdates to then leave a child with them for a week straight.
And remember, those days your child is in daycare, he'd still be with them from 6pm all night through 8am the next day each day.
To me, 3 is too young to leave any child with someone for a week that they have not already spent 2 or 3 days at a time with before the week long trip. And I'd want it to be someone I knew VERY well. It is amazing how much more you learn about people when you spend an extended period of time with them, and when it comes to watching my kid? I gotta know you way better and longer than for 3 months.
Is your only option an 8-9 day trip? No 3-4 day trips and do you have family or friends your child is already used to spending the night with for those 3-4 days?