Why would you want to do that when the battery is going to run out before you can even go the supposed longer range with it, making the mod pointless. The battery/flightime would have to be improved by 15-20min first. disco yes, anafi no.
I personally can’t see the point. The antennas housed in the controller are directional and thus provide some forward gain over the omni-directional (presumably sleeved dipoles) antennas shown in the pictures. They may negate the need to point the controller at the Anafi when out of the beamwidth of the internal antennas but not really any other advantage.