As others have noted, racing is an expensive game and not something you can do well when you're counting pennies. That said, you could start to leg her up (after a vet has verified soundness issues are resolved) at slow paces on hills. You mention access to trails and if you have some decent slopes as part of that it's a good way to start to put a bottom on her. No need for you to do much more than walking and trotting here to start.
At some point, you're going to need to move her into the track for speed work and additional conditioning. Sometimes you can strike a deal with a trainer - day rate reduced or waived for an ownership share of the horse and/or higher percentage of purse money - but usually the trainers willing to do this are not the successful ones. You'll also likely have high vet bill, blacksmith and other expenses once she's at the track. Even if you start with some early foundation work, it's probably going to be at least 60 days at the track before she runs, probably more. There are costs associated with this no matter how you do it. You might consider bringing in a partner who has deeper pockets if you really believe this mare has potential. As already pointed out, the nomination means nothing relative to her ability - but sometimes trainers with large stables will get a rid of a horse with talent because they have other horses waiting for the stall and don't want to invest in recovery time after an injury.