It's a complex interdependent set of calculations but in a nutshell extremely humid air needs a multi-stage evaporator or enough airflow through an evaporator to keep the surface of the evaporator coil above 32F
This cannot be achieved when moisture laden air is passed over a collector at less than freezing temperature. An A/C unit set on high fan will freeze slower than the same unit operating on less air flow through the evaporator.
In my environment it is counterproductive to try to force the A/C to do more than it's designed for...
The largest model dehumidifier extracts as much water as is feasible. The A/C is set on highest fan speed. When R/H lessens to <55% the dehumidifier can be shut off and the AC is left to continue to reduce air temperature into the high seventies.
Generalizations as offered by your dealer are worthless. In full sun near 105F and humidity >60% THREE TIMES the BTU are needed compared to 90F and 40% R/H
I am comfortable in 90F temps with 60% R/H.
Some folks cannot tolerate ten minutes at these values.
I keep harping on it but SHADE is the key. I had THREE roof 13.5K operating on a diesel genset and when I had a palmetto leaf shelter built for shade I reduced the AC units to one. This was in Quintana Roo. Outside air temp 105+F with humidity near 100% (condensing). Near lethal numbers.