Hi Rubysmommy,
Haven't got any great advice (sorry!) but I'm currently trying to do exactly the same as you with my 13 wk old. From my own personal experience, one formula feed in the evening has helped my babies sleep longer at night (this is my 3rd baby), so don't lose confidence that your idea is a bad one - it isn't! This method has also worked very well for many many of my breastfeeding mummy friends too....
My main problem is that my little monkey is currently refusing a bottle unless she's really sleepy, so I'm trying to do it as a dream feed, waking her up at 10pm-ish. If I try & give her a bottle at 7pm (her bedtime), she looks at me as though i'm mad! However, she will happily take a bottle for a dreamfeed.
If you can, express in the morning to give her the milk in a bottle in the evening - I find that my morning milk is of a 'better quality' (i.e. more filling / satisfying for baby) than the evening. Having said that, I am happy to use formula in the evening bottle - what with a school run / nursery run & a 3month old, I have little energy left to sit there with a hand pump!
Anyway, just wanted to reassure you that your idea is not a bad one, it works for many mums & is worth giving it a go / persevering if you feel totally drained & exhausted in the evening. Plus, dad gets to give the bottle to baby - my husband always complains that he feels totally left out during the breastfeeding stage of baby's life, so relishes the opportunity to feed baby once a day.
Good luck, hope you get some well deserved sleep soon x