Knowing which outlets are on which circuits is important, as you have discovered. My rig has 3 circuits with outlets. One is a 20 amp circuit without GFI, 2 outlets in the dining area and 1 in the bedroom. One is a 20 amp circuit with GFI protection, an outside outlet, entrance door outlet, kitchen outlet, and bathroom outlet. The third is through an inverter and is only 15 amps with GFI protection, both the front and rear entertainment centers.
That is knowledge hard gained, and long remembered. Space heaters go on the two 20 amp circuits, one to a circuit, but never on the 15 amp circuit.