If you do remove the plate for inspection, do not drive without it ,some of the bolts secure the sway bar...
Your best bet is to pressure test the coolant system, this will show you where the leak is...And if you can`t see where it is coming from...This is where it gets complicated.
Under the intake manifold there are coolant tube(s) that connect to the rear coolant pipe (connected to the rear of the heads) this tube(s) have O-rings that get stiff and will leak under pressure. The bad news is it very difficult to see in this area w/o taking parts out.
Good luck