I will just leave this here
You can make your own decisions
A Grade 8 bolt is very hard and under a shock can slap.
A Grade 5 bolt it kinda hard but has more ductility and will bend.
It can take Shocks and still be structurally sound.
I have been a Structural Steel Welding and Bolting inspector for 34 years and in Commyfornia with all of the Earth Quake crap they frown very heavily of the use of a Grade 8 bolt for Structural use.
I have seen Engineers spec out Grade 8 bolts but not very often.
They do not like brittle bots for Structural use due to the Shock values.
Just my opinion but pulling a trailer with the bumps and humps in the road.
That may create Shock on the Hitch pins
