Safe to use a 30 amp Extension on 50 amp trailer at home??

What I did was install a voltage cutoff surge protector. If it detects low voltage it will cut power to the RV. I only have 30 AMP, but ran it on 15 amp service for just the refer and AC, and last year it was fine, this year however it tripped a few times so I inspected the extension cord and found the plug was corroded. I have since run a 30 Amp outlet and made a 100' 30Amp extension for it. Now I can run it all.

This one here