On my dual extruder machines, I usually just have raised text extend both in and out of the main body by 2 layers...this gives them a solid anchor and makes them look good, too. I use a wiping tower to keep everything flowing well and clean.
With a single extruder machine, you could get or build one of various devices on the market that switch filaments for you and just make sure you use a purge block for the switch. Prusa's firmware isn't super good at doing this without wasting material, unless you print another object with the purged material (a new feature for them). EDIT: I forgot that now you can also use it as infill. Of course, that means getting their multi-material unit and updating the firmware on your printer to handle it...hopefully you can hook it up to your board (I think they've made it pretty straightforward, but I'm not sure...I use dual extruder machines when I need multiple materials).