I am not sure if you can change your status while being on TPS (without adjustment of status process). Once you are out of your legal status (say F-1) and decide to use the TPS - EAD after your current OPT extension ends, you have to file for adjustment of status to be back on F1 status. I believe, this status adjustment process applies to any change in status (say GC) coming from TPS.

**This is what I understand from my friends and reading the comments online. Experts, please correct me. However, if you want to play safe, there might be a 4th option.