I have a mare that's very 'hot' and excitable under saddle but she isn't spooky and would never dream of trying to run back to the barn etc
She is perfect where groundwork is concerned so I see that as a waste of time for you with this horse.
You have to learn to be a very relaxed rider - I had a lifetime of fizzy gymkhana ponies so to me she was no problem, I love her the way she is, you either like this sort or they terrify you and if they terrify you you will send them into a panic as they need cool and calm
I have long perfected the 'sack of spuds (Potatos) tied up horrible' style just for these sort of horses.
If you use more than a hint of leg it will be off but you need to keep them into the bridle on a light hand - any hint of a hard pull and that forward motion has a nasty habit of turning into an upwards one.
One point - is this horse 'hot' or is it fractious?
You might want the owner to look at possible pain issues - like in her back or maybe even ulcers.