Nothing is free. If you use the booster, it will pull more current and drag the voltage down for other sites on that same circuit. Not applicable if you are the only one on the circuit.
With only 30 amps fused at the pedestal, you have less than 30 amps available in the trailer at the boosted voltage. Again, nothing is free.
Besides that, the boosters technically violate the electrical code, although there is no one going around to enforce the code.
John W. Irwin
2005 Classic 28 "Sabre-Dog III"
2013 Silverado 2500HD Duramax/Allison LTZ
WBCCI #9632, TAC TX-10