I have always used the RV30A to 15A LONG DOGBONE type adapter like this one from WALMART...

This type of adapter does let the pins of the 30A Male plug get hot.
The small round type adapters like shown here are known to burn up your contacts and shouldn't be used...

They will burn up your 30A Plug contacts everytime...

Also if you are using an extension cord to get to your house/garage 120VAC receptacle use one that is 12GAUGE at a minimun. a 10GAUGE is even better. The cheap RED/ORANGE 14-16Gauge cords from WALMART doesn't do well...
I lucked out in my garage where I had a 20A Circuit where an Air Compressor was once used. Nothing else is on this 20AMP Circuit breaker in the power panel.
I found a couple of 50-foot contractor grade 10-gauge Extension Cords at a yard sale for my hookups.
I also use one of these RV 120VAC plug in meters inside the trailer where I can glance at it. It has the SAFE ZONES printed on the scale. I won't turn on my air conditioner if the Ac Voltage is out of safe limits...

All photos here from Google Images
Roy Ken