If you have a bare 1 inch of standover clearance, you'll be OK mounting and dismounting on flat ground. It's on hills where that clearance gets smaller and
maybe your body and the top tube meet. For years I rode a bike with a 23 inch
seat tube, and my inseam is 32 inches, leaving me with about 1/2 inch of clearance.
You can learn to be careful on the hills and tip the bike further to mount and dismount,
but occassionally you'll make contact. For me it was never hard contact or enough
to cause real pain. I suggest taking the bike to a steep hill and practicing there to see if you have really enough clearance. Try both with 2 feet on the ground and with one foot on pedal/one foot on ground. Of course, other frame dimensions are important too, and you might be prepared to compomise down to 1/2 inch of standover to get the other dimension right if you are confident in the dismounting on hills.