3 to 2 wire converter for trailer wiring

Can I build a converter with diodes?

My 1997 toyota tacoma has a three wire system with seperate stop and turn circuits. My small trailer has a two wire system with a combined stop turn circuit. I have been buying a reese converter/plug (part # 74672) for about $30. Due to  the beach environment my truck lives in they do not last more than a year. The contacts on the plug corode, break or otherwise wear out. What I want to do is use 3 diodes, one on each turn signal wire and one on the stop wire so that I can conbine the wires on my truck and use a standard trailer plug that is cheaper to replace. My thinking is that the diodes will prevent the current from flowing from the stop circuit to the turn circuit on my truck and allow my trailer lights to work properly. Will this work and what kind of diodes should I use?

Thanks