Don't be so keen with the switch
I run an srt101. I just turn the meter switch off when I get home and put the camera bag back in its proper spot at the end of the day. I also use that time to pick out any films for processing and generally clean the bag out of lolly wrappers, film boxes etc to get it read for the next time out.
Otherwise, while shooting for the day the meter switch stays on. Draw is low with the lens cap on, and it is even lower when it is in the bag.
There are instructions out there if you are not afraid to take the bottom off the camera and tweak a trimmer potentiomenter, to make it woirk with silver oxide cells. You use a second camera, grey card, and tungsten light source to confirm the correct exposure wrt shutter spped, aperture, and asa, then set the srt under surgery to match it, and then turn the pot until the meter needle matches the pointer circle.
I still have one mercury cell in the freezer awaiting its time to be put into service.
The existing mercury cell has been in the camera for at least 5 years, and is still going strong.