I do the same. The lower is much more critical to get torqued down correctly. The upper to lower (6 bolts) just tighten down snugg. I've never had an issue.
I agree on the lower...you wanna be doing it right...follow the tightening seq in your Haynes or the like...
I do 3 equal increments on the lower....with a max of 18-20. On the upper I snug em working from the center out using only one hand on the rachet and just ease em in, that'll get you right around 10 ft lbs or so, I double back with a TQ wrench after and go about 12-15 or so...You dont wanna be reefing on em as you can snap an ear off either part...Not good..
I would also suggest you use Allen studs or the like, 1 each corner on the lower to get the mother on and down even, otherwise it can shift while your tightening it...another not good..I throw the inner bolts in and snug em up, then pull the corners out, drop the bolts in and you should be good to go...some 2" Allens studs are el cheapo...bring a bolt to check the size...I wanna say its 1/4x18 or 20???