Hi,
It would really help to not have as many extension cords, as each connection can have a 1/2 - 1 volt drop across the receptacle and plug.
Do they have an electric dryer? If it is 4 wire, you can buy a 4 wire plug at Home Depot, a plastic junction box, blank cover, some wire nuts, and 50' or so of extension cord (might be less expensive to buy a 50' roll of #10 romex) then connect a 30 amp RV power receptacle at the very end.
On the dryer cord, you want to use the green ground, white neutral wire to the white wire on the extension cord, and one of the two red or black wires (but only 1 as you do not need 220 volts). Tape off the red wire, if you will be using the black one. Put all these connections in a plastic box with the blank cover and use the very large blue wire nuts to make these #10 wire connections.
At the end of the extension cord, use the 30 amp RV receptacle. You will notice that there is a LOT more brass in the 30 amp plug and receptacle than a typical home 15 amp receptacle. This leads to less voltage loss, and much better connection, less likely to overheat.
If the dryer only is 3 wire, then it would not be safe to connect your RV to this type of receptacle, as there is no dedicated neutral wire.
What I did once. Plug into the pits at Bowling Green Race track. They had some #2 wire overhead connected to #10 wire that goes down the power pole to a pair of 120 volt home size 15 amp receptacles - no fuses though. I plugged in a 50' long #14 extension cord across the parking lot, to a #12 25' cord with another 30' #10 cord to my transformer that boosted 100 volts to 112. Then plugged my 30' motorhome cord into that transformer. So about 145' total including the cords to the transformer.
I also needed to monitor the voltage, as it did drop, even with the booster plugged in. At 105 volts, I would recommend shutting off the A/C unit. Over 105, it will be fine.
WHen I lived on a farm, I was about 300' from the main house, on a power line to the pump building. It had a 30 amp circuit breaker at the house feeding $8 wires down to the pump building. I plugged in there, and would have 120 volts. IF I ran my microwave, the indicated voltage dropped about 12 volts. Running the A/C resulted in a 15 volt drop, so I predicted that I had about 1 volt drop per amp being used. By using the transformer, I got back to 132 volts (way to high to plug in the refrigerator to that voltage) and could run the A/C and still read about 118 volts with it on. I did not worry about the TV or other appliances having 132 volts, only heaters and the refrigerator.
So getting a Hughes Autoformer or other booster transformer will solve your problem, and let you use the 120 volt 15 amp receptacle on the side of the house. (yes it is only rated at 15 amps even if connected to a 20 amp breaker). It will also help out if you are using the dryer receptacle adapter, and still had low voltage.
If you find that you are plugging into the house outside receptacle, and when you turn on the A/C trip the circuit breaker only to find out that 1/2 the house or the bedroom receptacles are on the same circuit, you can normally safely plug in the laundry room - it has had 2 each 20 amp circuits to it if the home was built after 1965, per NEC codes.
Good luck,
Fred.
