Running Raid0 on MBP 2011
Solution 1:
If you have to stripe data across both drives, then you'll be constantly limited by the SATA II bottleneck.
You'd be much better off just buying a larger SSD for the hard drive slot, or installing two separate SSDs as separate drives.
At best, you might want to look at creating a Fusion drive between a larger mechanical in the Optical slot and an SSD in the HDD slot. (Or even two SSDs...?)