Are you sure the portable A/C would pop the 30 Amp breaker? A 13,500 BTU A/C unit actually only draws about 14 amps, it is just on a 20 Amp circuit. If it is possible, I would recommend you try the other unit with your current set up and see how it works, if there is a problem, then you could add the 110v outlet later. Just a thought.
Consider that the A/C and microwave operate at the same time and don't trip the main breaker, if the A/C is drawing 14 amps and the microwave 12 amps. That normally won't trip the main. Granted, you may not be able to run 2 A/C units and the Microwave at once.
A typical circuit breaker will trip within one hour at 140 percent of its rating. You may be surprised.
However, if you want to permanently install an rooftop unit, I would agree, you better add more service to your TT.
2008 Surveyor SV-291
2003 Ford 4x4 Expedition
Reese SC WD System 800/10,000 lbs
1976 Cessna 177RG
Wife, son, twin daughters, and mother