The answer to this question is a resounding "NO" you should not attempt to try this. I understand what you are trying to do, but if you do it the way you are planning to do it, bad things will happen to the electrical system in your RV.
You don't state what type of RV you have, but I can tell you that all RV electrical systems are designed to have electric current flow in one direction and that is from the RV's main power cord and then it is distributed throughout the RV from there. Trying to reverse the electrical flow will not provide power to the other outlets, but can cause damage to your RV's electrical components such as the Converter, Battery Charger, etc.
Even if it were possible to do this, you still would not want to. Take a look at the size of the power cord that your RV uses to plug into shore power, it is thicker then the wires that lead to the electrical outlets in your RV. That cord is designed to carry 30 or 50 amps of electricity. The wires that lead to your electrical outlets are usually designed to carry 15 amps safely. If you try to force more than that through those wires you can start an electrical fire.
The only way you should ever provide 120 volt electricity to your RV is by using the power cord that your RV is equipped with or by running the RV's generator.
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