Water Leak in Cowling??

The service mechanics most dreaded RO... wind noise and water leaks.
All day to find it and 2 minutes to fix it. Ford dealer had a shower stand made from a wheel ,some pipe and fittings, 6 shower heads. Worked good when hunting still car rain leaks . Aim rainmaker, stand on your head under the dash with a light. Repeat.
Just a thought but what if one of those hose attached bottles (like garden bug/weed killer) was loaded with water based paint pigment? Spray it all over the firewall and door jambs, into the cowling. Maybe work from bottom up ? Save the windshield for last. Use white pigment and go hunting with a black light ? LOL Good luck.