Unless she is a light widdler I doubt BGs would cope at almost 3. If you super boost them they tend to gape around the legs, especially if she is thinner.
I would recommend either Nappies by Minki or Wee Notions Night Notions depending on whether you want a pocket or a two part system.
Minkis are fleecy pockets which can be stuffed with just about anything, they can take a huge amount of boosting and mine have never leaked, even when inserts have been sodden. Fleece lined, which will help keep her drier too and aplix fastening to help get a good fit round the waist . Only drawback is they are HUGE and fluffy, but I kind of like a weeble bum at night time. Looks cuter
If you are happy to go with two parters then WNNN are just fab nappies. I use a few different night time ones but these are my absoloute favourites and have also worn really well compared to some of the others. Massively absorbant in the bamboo version, which again will help with keeping her dry and preventing a rash. I use with a motherease rikki wrap.
Night nappies can be costly. Might be worth seeing if you can borrow a couple or even keep an eye on classifieds for pre-loved to try before you buy. Some retailers or networks have schemes where you can too.