You shouldn't go for spray at all, if you're thinking of peeling it off one day. That's also what I meant by laying it right. I did this with a few of my kites. I found that if I DON'T thin it down with anything, I can dip the nose, and it will stay on but won't penetrate the webbing so much as I cannot peel most of it, if not all of it, off.
This is a kite altering process, never the less, and should be regarded as such. It's my personal opinion that if you don't want to take the risk of changing the way the kite was initially built, even in the slightest, you should not engage in this method. Results may be irreversible.
Since I'm a bit concerned regarding the ageing of the repair and the reversibility of the process, it was interesting news that you could peel it off even though you applied it on the fabric of the nose - a porous surface. So It didn't go into the fabric to any large extent, but more remained on the surface? Even when you thinned it by mixing it with naphtha it didn't enter the fabric so much, so that you couldn't peel it off?
No, I should start to make tests instead, I just saw an offer where I could get a spray bottle of rubber paint for about USD 9, as long as I freely chose the color blue. ... No I don't want a kite with a blue nose - I should go for the black or the transparent rubber spray instead.