Need to modify my ac but need an expert opinion?

I have a 02 sonoma 4.3v6 and I will be removing my clutch fan and instattlin a dual fan setup my question is since the clutch fan will be gone I will need to have the secondary ac fan configured to come on when needed my ques is that I'm unsure of what switch to use and where to put it I will need to have the line modified for one I don't wanna run the fan relay off the compressor because that would make the fan come on when ever the compressor is on and that is not needed when the vehicle is in motion and is just gonna wear out the fan motor faster and is an unnecessary draw on the electerical system so my main question is what switch should I use I imagine it'll be a 2 wire grounded on one side to use a negative to open the fan relay and engage the fan and ill cut the bung off for the switch off a line at the junkyard and have it tig welded to my line and where should I put it I imagine it will be on the high side since the high pressure getting too high is what will cycle it on and off I use my ac a lot so I want it to function properly I have guages so I can leave the car running for a while to make sure the pressures are proper and to make sure if the ac needs both fans to cool properly so I got that fig out just really need to know hoe to get the ac fan to cycle like it needs to