My contract gives them incentive to fire me--help

I will make it as brief as possible, but it is somewhat complicated.

1) I live in a largish city in the Midwest, and commute in for 4 hours every week to a small town where the hospital is located. The hospital pays mileage, and provides the hotel room. I work my 3 12 hour shifts, then drive back. I chose this option because I have friends and family in the largish city where I live.

2) I was naive enough to sign a contract when I was hired stating that, if I was no longer employed with them *for any reason* before 1 year was up (this coming October), I would have to pay them back all the gas and hotel fees. Since I am 8 months in, this is currently around $20,000.

3) I was hired on to a med/surg floor, which is clearly not a fit for me. I can do it, but the patient load (6:1, with the charge nurse also having 6) and acuities (high) makes for a VERY stressful night, every night. I arrive an hour early, off the clock, and often work an hour late. The management was angry at me for staying late, so even the hour late is now off the clock (I know this is illegal). They continue to add bureaucratic tasks for the nurses to do, putting me even farther behind. I sleep very poorly before shifts, because of the anxiety.

4) I am TRYING in med/surg, but I am terrified of making some small mistake, for which they could fire me. They do have a $20,000 incentive to do so, now, and it grows by the day. Even worse, I am afraid that I would make a mistake that would harm a patient. I feel that every night my license is at risk.

5) When hired, I made it clear that I was working med/surg in order to get training to transition into the rehab unit. However, there are no shifts available in the rehab unit, and it may even shut down due to low census. There are no other units that seem a fit for me, and I doubt they would want to train me into a third unit, anyways.

So, the question: I am per diem, and my contract only requires that I work 1 shift a week. This is what I will request, but how do I explain that to them without making it obvious that I will be leaving once the contract is up? Telling them that I will be leaving at the end of the contract only gives them more incentive to fire me. I would *like* to work full-time, just not in med-surg.

Is there some other way to work this out? Is the payback clause in the contract possibly illegal? I do have a tendency to miss the obvious, so thank you for any replies.
You are going to have to talk with an attorney who knows the labor laws in that state to get an answer to your legal questions. I suggest you do that before you do anything. You signed a contract and might be held to it. So be prepared.
OP, if you are set on remaining anonymous, I suggest you ask for a user name change. I am sorry about what you are going through and I hope everything works out.
Wish Me Luck, I'm not actually in Des Moines, but thanks. It is an old name. #LLG, I was really hoping to avoid getting that complicated. Only if I get fired would I pursue legal means. For what it matters, the hospital is not unionized. I haven't met any other nurses who have had the same contract as me; it seems it started with me.
Quote from DesMoinesRNWish Me Luck, I'm not actually in Des Moines, but thanks. It is an old name. #LLG, I was really hoping to avoid getting that complicated. Only if I get fired would I pursue legal means. .
Quote from llgYou are going to have to talk with an attorney who knows the labor laws in that state to get an answer to your legal questions. I suggest you do that before you do anything. You signed a contract and might be held to it. So be prepared.
Thank you to everybody who responded. The advice to consult a lawyer was a good one, and I did just that. His advice was that, yes, the clause would probably be held up, but in his experience it would be unlikely for them to fire me on weak justifications just to claim the $20k or so that is due. After all, they would be expecting a probably fight in order to actually get the money--and that may end up with them throwing good money after bad. That, alone, was incredibly comforting. I'm still going strong in med/surg, and I'll finish it out. Thanks to everybody.