GOOD DAY ALEX .
You say water is affecting your injectors , the electrical plugs on your injectors should have little rubber lip type seals in them .
Are the seals still there ? They do some times fall out when unplugged .
The signal pulse to the injector is running to earth through the water , causing the injector to lose power and not open .
Are the wires not perhaps cracked through the insulation somewhere ?
Any wires rubbed through the insulation somewhere , but not onto steel ? (the water is allowing the power to run to earth , even over plastic)
Your engine cover won't really help when you drive in very heavy rain , as the big puddles and fan will eventually push spray right up under the cover !
I hope I have given you some insight into the problem . (try to test one injector at a time to get a faulty one , and then to find what is causing the earth problem) . Remember , you have sprayed with clean water . Dirty water will have a stronger effect out in the bush , it conducts electricity better .
Now go fix it and maybe we'll see you guys out there !
Can we get rid of STUPID DRIVERS before they kill us ?