This explores the extended North-South resolution that could be obtained with antennas far to the south. The first plot shows the coverage for the VLBA alone on the same scale as the following plots.
The next plot shows the VLBA with an antenna near Quito, Equador. It would be slightly better to use the Galapagos Islands, but the logistics would be hard, I presume.
The next plot shows the VLBA plus an antenna at the ALMA site. Note the big holes between the VLBA and VLBA+ALMA baselines.
The next plot has the VLBA plus both Quito and ALMA. This is reasonable, but missing some coverage from the NE/SW direction. This would need to be filled by something in the South Pacific.
The final plot adds Easter Island to the above. Easter is nearly due south from the center of the VLBA so the tracks are short (similar absolute latitude, but opposite sign). But it helps. More antennas in the Pacific would be needed to do a proper job at the southern declinations.