Trying to use small inverter through cig. lighter adapter

Too much too small wire feeding the outlet.. The voltage is dropping under load.

you need to find a stronger wire in the bedroom.....

QUESTION, is there a slide out for the bed? and if so what is the make of the slide system,, Accu-Slice there will be a controller, likely either above the slide or below it a piece of fascia covers the area.. Tap the power to that, that lead can hauld hte freight just fine.