I always hate the struggle of leaving Jackson, so I know how you're feeling. My dad and stepmom are dog people, have 2 themselves, and have a fenced in backyard, I fully trust when Jackson is over there that he is being taken care of and is happy.
However, there was one time they weren't available and I had to leave Jackson with my mom and stepdad-both not into dogs like myself, or other side of family. I told my mom to be sure to give Jackson wet food mixed with dry food or else he wouldn't eat all day (esp. with me not being there). Yea... whoops she forgot. Among a few other things. I just don't trust them at all... BUT Jackson was fine when I got back, and happy, so I think it will be ok. And that was for 4 days. I think we just worry more sometimes than we should but of course you want to be able to trust who is taking care of your baby. I think if it came down to it again, if I was leaving for more than 1 night... and my dad wasn't available, I think I would find a nice doggy daycare rather than leaving them with my mom to be honest.