What ZaneO said. AIO never did any correction for me and it never hid anything either.
In this case I don't know if I'd try to fully correct the marring for this show. You'd hav to get the stuff (including PC, which I think you'd find useful anyhow) and work with it.
For now, I think I'd try to correct the worst spots with something like Scratch-X and use a polish with some fillers on the rest. Maybe Mother's Power Polish, though I haven't used it myself. Meguiar's #9 comes to mind too. Then a product that hides stuff, like Meg's #7 or 3M IHG. Then a LSP (maybe NXT topped with a carnauba) that also tends to hide stuff.
Note that many cars do well in shows despite having marring. There's a lot more to showing well than having marring-free paint.