i would weld the front and the back but leave a gap where the shock can sit flat. If it were me using that, i would use two top plates, it wouldn't sit well for me to have a single shear grade 5 bolt holding my shocks on.
As long as you have adequate bump stops there should be no issues with a grade five bolt in single shear. Shocks are meant to dampen the shock loads on your suspension, not carry the kinds of loads that require grade 8 bolts or even double shear.
