Hi Jeff,
You have a total of 32 registers (R0-R7 in 4 banks Bank0 - Bank3). So, you can increase your variable count to 32 straight away. One caution. When you refer to a register number like R2, the R2 register of the active bank (specified in System Flags Register)gets called. To access another R2 (of other bank), you need to change the active bank. Now, if you want to avoid this (I Mean your program permits this), then you can directly refer to the registers using their addresses ...00-R0 07-R7 (bank 0)
08-R0 0F-R7 (bank 1) and so on.

Regards,
Harsha