I heard the ideal portable solution is to carry as many machines as you can within a portable wheel driven suitcase.
The issue isn't how man machines you have but its actually the bag you have.
Let me explain, the bag you have dictates how many machines you can carry with you.
Therefore picking the ideal bag will dictate how many programs and machines you can run at any given time.
As @
556fmjoe says, run one program per machine. So if you find the right bag / case to carry one machine per program you are set. No more slowdown or risk of your MacBook Pro running too hot.