Spray tan to fill in tan lines - is this a thing?

[anxiousanxiousness]

I've spent the day at the beach and managed to burn my back. I was wearing a strap top so it's only the top third of my back. I'm going to a wedding this week and the dress I've bought will nicely show about 2-3 inches of pale skin underneath, what should hopefully by then be, nice brown shoulders. I've never had a spray tan or used fake tan before. Is it possible to get a spray tan to match the lower part of my back to the top? Is a spray tan likely to rub off on my dress (it's royal blue so I'm not sure how much it would show anyway), or does anyone have any tips for how to cover up the ridiculous stripe on my back for one day?

Just do a fake tan/spray tan all over and it will even it up, the tan will develop more on the untanned skin than the tanned skin so it will defo look better.

Yes, don't try to just fill in the white bits. I once tried to paint in my friend's tan lines with fake tan and the colour totally didn't match.