You are putting yourself in a complicated situation which might or might not work as the decision is not yours, its USCIS who decide your F1 or F2. Since you are already in TPS with EAD and F1 status as backup, my suggestion is to maintain the same for betterment. If TPS is not extended, you can still be in F1 and complete your degree, why do you need to be dependent as F2. Do not do it. Once you complete your degree, apply for H1B that gives you 3+3+1 years of working status and path to Green Card through sponsorship (Eb2 or Eb3).