What Happens If I Return to Thailand Before My O-A Visa Expires After Obtaining a Re-Entry Permit?

I am currently in Thailand on an O-A visa which expires on 29 Aug 20. I am stamped in until 14 Jan 21. I plan to leave the country on 13 Apr 20 and return before the visa expiry date in Aug 20 and get stamped in for a further year (less 2 days). However, due to uncertainties with covid-19 restrictions, I may well not be allowed into Thailand before my visa expires. To mitigate that eventuality, I am considering obtaining a single entry re-entry permit before I leave to keep alive my stamped in date of 14 Jan 21. My question is this: If I do actually manage to enter before my visa expiry date of 29 Aug 20, what will happen? Will I get stamped in until 27 Aug 21, or will I only get stamped in until the current exit date of 14 Jan 21. Which takes precedence, the re-entry permit, or the visa?