What do you mean when you say spray can will not hold up very well, Baron?? In the picture at the top the whole back half is spray bombed, and it held that way for a year and a half. and it was one coat of trem clad semi gloss on a non sanded clear coat. So i don't know what you mean.
The main reason you don't know what i mean, is because you haven't been doing top notch refinish work for almost 25 years.
Don't misunderstand, that i realize you aren't in any way trying to do that anyhow. That much goes without saying.
Soaking wet with the water still running off the car - as it is in your picture, even primer can look okay.
A semi-gloss like you used before is going to be harder to gauge the rate of deteriation - as opposed to the Gloss finish you are going for now.
Do your car exactly the way you feel like doing it.
You've definitely got it by the balls there tiger.
But i have seen a couple oil base exterior enamel paint jobs sprayed on that looked pretty spiffy for the coin spent (well...not spent). And they held up fairy well for about 3-4 years. But they were not Black (fwiw). And they were not mine.
I have never seen a Gloss rattle ball painted hood or trunklid that still looked good (glossy with reflection and distinction of images) for more than a month or two, of normal driven operation. Keep in mind i'm not talking about buffing it or polishing it to try and maintain it. But one coat won't handle very much of that anyway.
If you keep it in a garage and never drive it but small amounts in fair weather, it could go longer. But gloss black, from a rattle ball sprayer, is about the worst choice there is.
This is just friendly advice.
And your hood looks like pure hell.