That latch sounds like the kind of thing my grandpa would've just whipped up in an afternoon. One trick with old flat iron like that is to heat it dull red before bending, otherwise it can crack at the corner. For your copy, use a piece of mild steel at least 3/8 inch thick and drill your holes before you do the bend, not after. And don't bother with paint, just oil it once a year and let it get that gray patina, it'll outlive your shop door.

Rubbing alcohol on fungus, swear by it.

Oh man, the FR-301 is a game changer, but I gotta nitpick one thing. Phoenix humidity isn't really what makes pads lift, that's more about heat and how long you're holding the iron on there. The wick and bulb just take longer, so they transfer more heat to the board. Still, yeah, the gun's a huge upgrade, I just wouldn't blame the weather for the old struggle.