I think I may be having a grumpy day but the advert suggests to me that you need help with your horse during the week and expect that helper to exercise and school and pay you.....doesn't sound so attractive and I am sure not what you mean.
I personally would start as if you are trying to sell your horse to a sharer, there do not seems to be many negatives other other than lacking schooling and being a bit strong. So after you have attracted someone in the first few lines mention that she would suit a competent adult with own transport to the yard and that you are looking for someone to have a three day share , days by negotiation.
It will say everything you have but just angle it to be more attractive rather than suggesting you 'need'
I personally would start as if you are trying to sell your horse to a sharer, there do not seems to be many negatives other other than lacking schooling and being a bit strong. So after you have attracted someone in the first few lines mention that she would suit a competent adult with own transport to the yard and that you are looking for someone to have a three day share , days by negotiation.
It will say everything you have but just angle it to be more attractive rather than suggesting you 'need'