The step through are going to be heavier as the true "ladies" bikes are not being sold in the states. One option to consider is adding a dropper seat post to the bike. This would make it easy to drop the seat to the height of the top tube to mount or dismount and quickly raise it back to the best height for riding. I had this done on my hardtail bike as a retrofit and it works very well. Dropper posts come in different diameters to fit any seat tube on a bike.
Something else to try is having the bike nearly on its side or about a 45 degree angle with the ground. This makes the bike much shorter for swinging a leg over the top tube which is a foot or more closer to the ground. My wife needed to use a curb before she started to lower the bike in this manner.