IMO its going to be very close, as your existing roof air draws very close to 15 amps, and I would guess your 8000BTU portable is going to draw at least 12 amps, probably closer to 14. If you run virtually nothing else, no TV or ??? you may make it, but your talking really running right at the margin. If you are camped where the pedestal has a separate 15 amp receptacle and you could plug your portable into that, it would solve your problem. Also you are talking, probably, about plugging the portable into one of your interior 120 volt plugs, be sure it is a 15 amp circuit, and nothing else is plugged into that circuit. Its going to be kind of a tight rope walk, so to speak.
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