LocalgHost:
currently using an Uno ( Atmega 328)
So I'd like to keep the RAM usage as low as possible
Certainly understandable but before trying to reduce SRAM usage you need to first determine how much is being used. This is from the Uno webpage...
Summary
...
| Flash Memory | 32 KB (ATmega328) of which 0.5 KB used by bootloader | |
|---|---|---|
| SRAM | 2 KB (ATmega328) |
...but this results in a lot of memory usage ( 7k [SRAM] )...
How did you determine that your library is using 7 KB of SRAM?