I have swapped the dash with the windsheild in place , I can tell you I simple could not have got the bolts in by the defroster vents by myself , I tried for over 2 hrs before my customers GF came home , I simple could not get my hands into the vent to put the bolts in place , her hands were much smaller & she installed the 4 bolts , I would still be there !!
The windsheild is usually the last piece I install besides the antenna mast if it is a non telescoping one