1 1/2 to 2 years ago 64gb ssd was the norm. You must perform most of the ssd optimization that leaves only the operating system installed on ssd and nothing else if possible. Create new folders and move all the operating system ev, variables, temps, etc to the HD. Install all of your programs on the HD including PD. Avoid those few programs that insist on installing on the C drive and find alternatives. The majority of my Cyberlink softwares installs on the HD if you tell it to including the suites.
My Win7 64 bit system has 8GB free on the ssd boot drive. Edit and create 24GB HD BD successfully with no problems. Sometimes in less than an hour. If you do the proper setup then PD will run great.
Google ssd optimization and perform all of them except the one for default program installation. I and many others are happy and successful with a small ssd when they came out.
I agree with others that a larger ssd is the way to go today. That will save you a lot of headache if you don't know how to do it.