First answer - call TRS.

Second answer - There are rules and limits. I do remember when I retired (eight years ago - stuff may have changed) that there was something in the literature about retire rehire, half time/full time, etc about this. Specifically addressing the 'loophole' some had tried to exploit (read 'some' as 'coaches') of getting around the halftime restriction and the ISD penalty for paying a nonTRS 'teacher' by hiring them as a private consultant...who was in the weight room all day supervising strength and conditioning (for example). TRS specifically said this was a no no. Didn't just apply to the extreme I mentioned.

Short answer - TRS sees this as trying to work around the retire/rehire regulations. There are rules and limitations.

Third answer - Call TRS.