I guess the first few steps are to make her feel sexy and desirable, boost up her self confidence, maybe introduce a dildo significantly bigger then your cock and let her embrace her slutty side. Baby steps...
Convincing her is like selling her a bill of goods. If you care about her, you have to cultivate that lifestyle change. If ultimately she isn't interested, don't ruin your relationship over it.
She's got a good little figure on her, and she doesn't mind showing it off (on holiday at least). Be careful and don't harm what you've got - but there are lots of guys on here who can advise you.
I think maybe we can help better if you give us a little more info. Is she a very sexual person(with that body I hope so)? Do you indulge in porn or have adult toys?
fucking hot as hell...she is! Take notice when you 2 are out socially or on a date. If she does not check out guys, there is always fantasy role play. Work up to it gradually. Don't be attached to outcomes. Even trashy novels (for her) could mutate into something 'dirtier'. Be creative w/o being pushy.
Let her know that the guys that you know, and that are around, have been saying complimentery things about her. You might even let her know that they thing she's got a "really nice ass" or "a great set of tits". What woman could possibly be offended to know that other men find them attractive?
Pretty much, just watch some black cock porn wit her, Get a flick with some big black guys fucking some cute little white girls, once she sees those big black cocks going in those tight little white pussies she will be begging you to let her try a BBC.