The carbonation chart that will help you to figure out the PSI to set the kegs to...
Force Carbonation Chart - Kegerators.com
I have a couple of weather station remote probes inside my brew fridge. That way I can tell what it is at now, plus the high/low temperatures (to get a better average). I also have thermometer strips on the kegs, so I can get a reading on what the brew temp inside the kegs is. The brew is usually about the average of the high/low range, depending on where in the fridge it sits.
BTW, 5PSI at 38F gives you only about 1.9 CO2 volumes...
One of the things I've been doing, since I split the batches into two 3 gallon kegs. Once I've purged the atmospheric air from the keg, I get it to about 15psi at room temp. I shake the keg (more like fast rocking on the floor) to get the CO2 into the beer better, alternating between the kegs. I then put the kegs on the gas half a day at a time (again, alternating) for a couple of days. Then I take them off the gas and either put one into the fridge, or put them aside to wait for an open spot. This way, the brew is partially carbonated before it goes into the fridge. I use a pressure gauge on the gas post before I put the keg into the fridge, and bleed off until it's at about 10psi. Then it goes in, and onto serving pressure. This has worked rather well for me so far. I do occasionally test the reserve kegs to see what pressure they are at. Pretty much always right where I left them last. I do find that this partial carbonation mode helps me to get to the carbonation level I want in the keg a bit faster.
There are plenty of ways you can alter the carbonation method to fit your needs. Start with the common methods and alter to fit your hardware, or desires.
Most of my kegging hardware (except the kegs) has come from Keg Connection too. IMO, they're still a small enough operation to care, but big enough to get the items we desire. I'm actually working with Todd on an order issue now. I'm waiting for this to be a done item before I post up any info about it. I will say just this, I've been on the phone with him twice on it so far. Once last week, and once today. I've also worked with other people from Keg Connection on either tweaking orders, or ensuring I get the correct item, before. Typically it's all good when it arrives.