Trailer Light Question?

[Cappy]

Ok I have an 18' triton on an aluminum trailer the lights are old dont work half the time and I am thinking about rewiring it the old school country boy way. Thinking about just using an extension cord wiring it up leaving the wire tie wrapped to the frame for easy futue access. My question is this there are a couple little yellow lights on th frame in the mid point that I dont think have worked in years do they hafta be there?? Can I put reflector tape instead or just wire the tail lights and be done. Is there some law I dont know are they just there and can be forgotten about??