I'm similarly vertically challenged, and I've found that the best approach is to do everything possible with the seat and with your riding gear to improve the situation first. The very last thing to consider should be shorter shocks, because as you've found they have shorter travel and thus tend to be harsher. Sure, you can buy very expensive custom made shocks that might work better than the off-the-shelf Progressives, or even more expensive air systems with onboard compressors, or you could even spend a ton on a reverse gear setup I suppose. I managed to solve my problem with a new pair of boots when the local dealer had a sale, less than $100.
What kind of riding boots do you wear? I found that switching from my previous brand of boots, with a relatively thin heel and sole, to a pair of Harley boots with a very thick heel and sole, made a world of difference in backing the bike. I hated parking at the pizza joint Momma and I used to frequent because the spaces all had a slight slope toward the curb, and when combined with the inevitable loose pebbles and sand it was almost impossible to back out. First fix was to back into the space so I could just ride straight out, but after buying a better pair of boots I could do it either way.
Just a thought.
Jerry