You don't need to put the SSD drives in hardware/software RAID to benefit from the extra storage. If you want to install programs, simply create the Program Files and Program Files (x86) folders on the second SSD, and when installing new software, point to the new drive letter when it defaults to C: (i.e. if the SSDs are C: and D:, when a program installs to C:\Program Files, change it to D:\Program Files).
Since no one uses a command prompt to launch programs, and you are just clicking on icons, what difference does it matter which physical drive letter the programs are installed on? Using 2 drives with 2 drive letters wouldn't make a difference in normal activities.
RAID, when used in the enterprise level installations (i.e. Database Servers, File Servers, etc) provide large capacity volumes, spanning multiple drives, with redundancy - and quick replacement of failed drives. Using it for home installations will create more headaches than it solves problems.
Since the SSDs would be a spanned volume, and no redundancy, if either drive failed or had issues, both drives would be useless.