Bruce
TVWBB 2-Star Olympian
These are the ones I got. Not sure if the 1/2" would be long enough or not. If they have 3/4", you could go that route.
https://www.boltdepot.com/Product-Details.aspx?product=22054
https://www.boltdepot.com/Product-Details.aspx?product=22054