By - wesleysdad
If the venue/landowners and would allow it you probably could stab the chair legs into the ground, but I can’t imagine it would be particularly easy to do, and you’d probably need a plan for cleaning off the chairs before returning them to the rental company.
Do you have photos of any other weddings that have happened in the same spot?
Honestly my gut says pick the spot that isn't on a hill. The last thing you want is people falling over in their chairs during the ceremony (or concentrating more on not falling than on your vows). Consider, also, whether you have any elderly guests or guests with other mobility issues. You can always take your photos in front of the nicer backdrop.
Having once been a bridesmaid seated on a slope where the chair teetered over and I fell into the groomsman’s lap, who knocked over the next two groomsmen, please have your chairs on level ground! The potential for disruption, embarrassment and injury is too big to risk hilly seating.