What a wonderful thing - thank you for rescuing Lucie!

How about a cat tree? There are so many different styles to choose from! Cats generally love them - whether they're up on top of them or underneath them.

BTW, there are some things you can do to help socialize Lucie.

Do you already use Feliway? This is a synthetic hormone that mimics the "friendly" markers in cats cheeks. ...just make sure you don't spray it near her litter box(es) or scratching posts.
You can get a t-shirt really good and sweaty, and put it under her food dish. This will help her associate your scent with good things.

If she likes playing with an interactive wand toy, get another t-shirt good an sweaty, and after a good play session, set treats down for her on that. (BTW, if you don't have a cat toy called da Bird, think about trying it! It has feather attachments or a mouse attachment. I thought our kitties went nuts for the feathers - until we tried the mouse. It's smaller than it looks in the pictures... and I don't know what it is about it, but they went NUTS. Lazlo did a back flip trying to catch the thing.

).
Also, there's something about harp music and particular kinds of classical music that feral cats really respond well to. You might want to consider playing these for her?
http://www.musicmypet.comhttp://www.catfaeries.com/music-for-cats.html
At this point, do you mostly just ignore her? For our gang, that went a long way to making them comfortable.
With ferals, it's all about building trust. Of course, personality is a big part of it. The first feral kitty we rescued was about 10 weeks old when we rescued him. He turned 7 this year. He does sleep on the bed with us, and he did come to love being petted and brushed pretty quickly. But a good cough or a loud noise and he'll flee... and he hides whenever we have company over.
But it took years before he was willing to sit on a lap. Even now, it's only in the bathroom when he's being brushed.

But we found that the key to building that trust was just giving them food and water, cleaning their boxes, and making sure they weren't bored... and working on getting them to associate us with "good" things using our scent and food.
Other things you may or may not know:
Looking a feral cat directly in the eyes is a sign of aggression. Look at Lucie on the forehead, or over the top of her head. Also frequently "looking" at her with your eyes closed - or at her forehead and doing a long slow blink - is a trust builder.
Best not to reach out toward her at all until you've crossed that trust bridge. But if you have to, for any reason, do it with your hand palm down. Cats are the opposite of dogs this way.
Right now, she doesn't "get" that you're "good" yet.

People are big and walking towards her is probably still scary for her. Spend as much time as you can down at her level. Don't sit facing her, but sit on the floor with your side to her - at a 90 degree angle to her. Read a book out loud, sing, work on a laptop, fold laundry - whatever you can think of to do. And just talk to her, softly. Tell her what a good girl she is, how much you love her, and you know how scary it all is, but she's safe with you.

Hate to say it - but we talk to our kitties with a kind of baby talk.

Do things like yawn and stretch - cats can relate to that.

The idea is to just let her watch you being completely non-threatening - and down at her level, you're a lot smaller and a lot less scary.

...but even now, when we feel like we're not getting enough attention from our kitties, we just start ignoring them, and we stop seeking them out or trying to pet them or whatever. Give it a day or two, and they're all over us. (Obviously I'm not suggesting she'll come around in a day or two, but when she finally figures out you want nothing from her and that being warm and fed and played with is good... well...

)
...and if you're handy - you can custom-build a cat tree for her. But google cat condos or cat trees - if nothing else, you'll get great ideas on what to build for her.
