I dont think a little recess is going to affect the strength of the car if its welded in. You wouldnt even need to go 10mm deep with the recess.
If you cut into the bonnet frame and dont weld in a plate, it will look ugly and if you cut it out altogether your bonnet will bounce around.
As you have no welder, maybe best to take the radiator and get an angled pipe welded on so that the outlet is more directed in the direction it needs to go. (edit I now see its only aluminium intercooler and plastic radiator tanks. Cant really weld on a new pipe now.

)
I wonder how many dodgy 1200s are out there with rubbing bottom hoses?