Overall, I agree with the suggestions above.
I have had to repair several leaks similar to what you have and having said that, it is mostly leaking around the access plate or at one or more of the screws.
It doesn't look like you have a gasket under the plate, so that's promising.
I will also say that sometimes the leak isn't where you expect it to be and the fuel is traveling.
If you touch the proseal with your finger and it is sticky, it is definitely leaking through the proseal somewhere.
Based on your pictures, there isn't an obvious spot to zero in on.
Check all the fuel line B-nut connections to make sure that isn't it.
The soap bubble test is worth doing but you won't be able to see the back baffles, which could be the source.
I would go for the simple solution first.
Clean it off as good as you can.
Spray some developer, from a dye penetrant test kit, on the area. It will leave a whitish powdery look. Let it set over night or go flying and any fuel seepage or leak will show right up.
If that doesn't work, I'd just take the tank off and test it with soapy water. VAN's sells a kit for this, but I usually just tie wrap a balloon to the vent outlet, close off everything else with a plug or tape and use some air pressure to blow air into the fuel outlet and blow up the balloon. (The balloon will keep you from over pressurizing the tank.) Use a piece of nylon tubing or something to blow the air in and then fold it over and clamp it to keep the air pressure in.
It's not that difficult, just a little time consuming.
Good luck