starter relay issue

I am on my fourth or fifth starter relay, about one a year. I replace it....works like a charm for a while, then nothing except a faint click.

I have a switch that kills all power, basically disconnects it when not in use The juice comes right off the battery....replaced one battery already only because early on thought it might not be getting enough voltage with the battery located in the trunk. Never had an issue with a trunk mounted battery in the past and doubted it...but wanted to take it out of the equation

I even relocated the relay outside the engine bay thinking all the aluminum was putting out too much heat.

any ideas and suggestions welcome.