Welcome to the forum. I hope that you will find many opportunities to participate now that your lurking days are over.
There are two factors in 110v power cords - length and gauge. Let me see if I can help you understand the gauge part.
Suppose that you had a water tube that was 100 feet long. You could get all of the water that you need from it right? Probably not if that tube is only a quarter of an inch in diameter..
On the other hand, a 100 foot hose that is 3/4 of an inch in diameter is going to deliver a lot more water. The question is will it fill a swimming pool quickly? Probably not.
The same is true with electric cords. In addition, the longer an electric cord gets, the greater the voltage drop. There is a formula for figuring that out but let's not get too technical with this yet. The important part is that you understand that, like a pipe, an electric wire is designed to carry a certain amount of capacity.
Let's suppose that the voltage where you plug in your TT is 118 volts. That's good. But now you put together two 50 foot 22 gauge wires and your voltage where you are trying to run an air conditioner is suddenly 99 volts. What happened? A humorous but somewhat accurate answer is that the wire ate the difference in voltage. Actually, it just won't let that difference pass.
For a long run, you need to use a much heavier gauge wire. Here is an example
US Wire and Cable 99100 - U.S. Wire Extreme Cold Weather 100-Foot Extension Cord (12-Gauge)
Notice that the cost is a lot higher than the wires that you can get at the local home improvement store. But the gauge on that wire is not going to drop the voltage as much. The same is true for the type of wring that is inside your house. If the runs are long enough, those wires will drop voltage, too.
I recommend that all RVers get a VOM (Volt Ohm Meter) and learn how to safely
use it. Even the very cheap meters at Harbor Freight that cost less than $5, will tell you what your voltage is at the air conditioner at the end of a 100 foot extension cord. If that voltage is too low, you will burn up the A/C unit with continued operation or it may not even start. That is because the electrical "pipe" is to small to carry the capacity of electricity that is required.
I hope this helps.