Hi @ArtyCele,
Custom fields for activities are currently not supported, unfortunately. Other users have however requested this before: https://community.hubspot.com/t5/HubSpot-Ideas/Custom-properties-for-Activities-Tasks-Meetings-etc/idi-p/204853
The product team reviews these requests based on their popularity. I’d recommend upvoting and commenting. You can also help others find the request more easily (and drive traction) by accepting my reply as a solution. I’d appreciate it, too!
Generally, it does however sound like your AEs and BDRs should both maintain information about who should be contacted or not on the contact record. It would be a change in the mode of working but storing this information in tasks would not be good data hygiene.
Best regards!