Hi sid, I'm not sure what your miracle grow sack is I only know the miracle grow plant feed, so I'm assuming they are similar to our 'grow bags'.
That being the case you most certainy can; here in the UK grow bags are used extensively and as you say all you do is to lay them flat and cut holes in for planting and for watering plus a few slits on the underside to allow excess water drainage, but not necessary if you water carefully.
I would think best for bush varieties and if growing indeterminate types restict to 3-4 trusses.
Many are sold as 'tomato grow bags' having fertilizer added to suit the tomato. Others as general grow bags for shallow rooting vege and for annuals.
Handy where there is little or no gardening space.