That alone isn’t a reason for her to need regular bathing.
Bathing should only be done if there is a medical need to do so ie a piggy has arthritis and simply can’t reach round to clean themselves clean anymore.
Cut her hair short around her back end and legs so it doesn’t drag on the ground (keep it up as regular maintenance), doesnt tangle or get soiled. Brush her hair. This alone should mean she never needs a bath.
If she is smelly and soiled now due to hair being too long, then cut her hair and give one bath ideally with plain water as much as possible get her clean. One shampoo may be needed if soiling is particularly bad. With routine hair maintenance (cutting and brushing) and no medical reason for not keeping herself clean then she should not need another bath.
If she still gets soiled because she is sitting in pee then find out if there is a medical reason for it (ie a UTI or if she is elderly has arthritis) and then if an occasional bum bath is needed during a period of illness, ideally just use plain water or wiping with a cloth as much as possible.
If you absolutely have to use shampoo then don’t let it be often and certainly never regularly.
Regular bathing or using shampoo is not good for them as it strips the natural oils from the skin.
My rainbow bridge long haired boy only ever needed one quick plain water bum bath in his six years because he sat in a fresh pee puddle and got wet. The others are semi long haired on their back ends (they’re actually short haired piggies but with long hair down their back end - they clearly have long haired ancestry somewhere!) and haven’t needed baths when their hair is kept in check.