I turn to the craftsmen to help me with a common issue... The Neck dive.

I am looking for simple methods of balancing out my guitar so it doesnt dive as much. I know I could use a better strap etc....but is there something you guys do solve this small issue?

I dont necessarily want to drill or modify the guitar, but to possibly add wheel/tire balancing weights (the adhesive kind) somewhere in the electronics cavity. Would this work?

The guitar I am trying to balance out is a Schecter Tempest Custom.

Probably, but it is not much you can stow away in the engine room. Materials that are dense enough to serve as counterweight are without exeption metals that must not come into contact with the electronic components, making this problem bigger still. These tire balancing weights are quite tiny, as they are supposed to counterbalance a few grams at most.

An absolutely non intrusive and very easy solution would be to gaffertape a sufficiently large chunk of lead to the guitar strap close to the lower strap pin.
Downside is that the overall weight of the guitar will increase, possibly compromising comfort.

Another trick doesn't have this disadvantage, but will need some slight modification to the guitar itself. It is shimming the upper strap pin so the strap comes further away from the horn. A longer screw through- and a spacer underneath the strap pin might do the trick. It may well be that only half a centimeter is all you need to bring your head drooper into a nice equilibrium.
You can easily test the feasability of this solution by replacing the strap pin screw for a screw that is a lot longer so you can move around the pin and experiment with several alternative positions. With these results it will be easy to calculate the size of the spacer.