I've got a cheap flight booked from CAI-ADD(overnight)-JNB with the final leg on ET arriving at 1305 at Terminal A

Was looking at adding an extra flight to go JNB-MQP (domestic) on SA which departs at 1530.

From the replies I've read and the sticky, it sounds like this would be do-able but slightly tight but just wanted to ask for more opinions on this, especially the expected arrival immigration line at this hour of the day

Given the potential tightness of the connection, im thinking doing carry on bags only will save some time as well

Thanks in advance!