It looks to me like a combination of problems. When I paint in the heat I usually let the coats dry a little longer. Also use a little more reducer. It helps the evap process. When your paint is too thick and too wet, the layer you lay down on top "pulls" the wet paint from the first coat as it dries. The more you spray, the more dramatic the deformity of the paint becomes. Imagine the millions of "bb" like solids in the paint all running together in mounds and the thinner running like water in between the hills. The mounds take forever to dry. So, spraying color is a dance between hardener, solids and reducer. Always different depending on humidity, air temp and paint type. I keep a log of what works well and the temp and RH that day.
Next point is the gun. A conventional spray gun works by blasting a lot of air past a lot of paint and creating a big cloud of atomized "bb's" that land on the surface. An hvlp gun uses much less paint and a very focused small amount of air to do the same thing. If you let the paint from the conventional gun blow back or fall onto the surface, it "mounds" up as the paint you sprayed starts to dry. The hvlp gun minimizes blow back, but does not eliminate it.
Most guns out there have a manufacturer recommendation for where to start with the paint flow knob and the airflow. Airflow max is usually printed on the gun. I have used a lot of guns and if I don't know the specs I start with 2.5 turns open on paint flow. Then adjust as needed. I know everyone says paint the second coat after flashing, but that only works if you have the correct paint,hardener, reducer mix. Otherwise you can avoid some of the issue by letting each coat cure then spraying the next after a light wet sand scuffing.
I'm a self taught painter and just started on tractors but I've done a lot of spraying on autos both base/clear and single stage paints and you have a pretty classic problem. Improper gun AND paint mixture for the environment you sprayed in. Hope this helps.