Feel for her to downshift the tension. As you ride around the jump, when she starts getting tense, drop the contact of the inside rein for an instant and quietly regain contact. Feel for another tension downshift. Every time she downshifts the tension, praise her.
When she starts quieting down, approach the small jump at the trot. Do NOT hang on the reins/bit. If you have to half halt, immediately give the reins some slack to keep from hanging on them. This slack sends a message of non-tension to the horse and may encourage her to downshift a bit.
The next time you approach, she will probably try to rush. Circle her in a figure eight on each approach, practising YOUR mental calming exercises. If she approaches it in a calmer manner, reward her by letting her trot over it.
Keep doing that and keep working on calming your mind down as you ride. You will find that the calmer and softer your riding is, the more she is likely to relax. This is retraining your horse so keep doing it for a LONG time until she jumps quieter consistently. This will help, trust me.
I get students with this type of tension between horse and rider all the time and I can almost always cure it. YOU have to be the one to break the tension, not the horse.
Riding a hot horse requires and mental calmness from the rider to diffuse the tension. Otherwise you two will be fighting each other forever.
My first dressage instructor at age six was a German master, Capt Heyer. My favorite saying of his (in strong German accent) was;
The tenser the horse, the softer you ride.
Try it, you have nothing to lose and much to gain. I just wish you lived closer to me as I would gladly help you two.