Upvote:1
There's always a possibility that she can get a visa. The only way to know for sure is to apply and see what happens.
Since you don't have concrete plans for the trip, the visa application must be filed with the Schengen country you plan to enter first -- which, coming from the UK with a vehicle, would probably be France. Also remember that the visa application must be lodged with the French representation in South Africa; one can't usually get a Schengen visa after leaving one's country of residence.
Since we're assuming that you can demonstrate sufficient funds, the only loose end should be demonstrating sufficient ties to South Africa to convice the consular officer deciding the application that she intends to return there after your trip. At 50 she doesn't really fit the typical profile of someone who's willing to throw away everything for an uncertain future as an illegal immigrant, which is a good thing -- but what the deciding officer will require to be convinced beyond that is anyone's guess.
A steady job would help with that, of course, but it's not the only way to proceed. If she owns property or has children/grandchildren living in SA, definitely point that out. Or if she has lived at the same address for many years, document that as well as you can; that too is a sign she actually lives it there.
Do what you can to document the length and stability of her relationship with you. If you're not married, then she doesn't get any definite rights from the Freedom Of Moment directive, but the directive still exhorts member states to be particularly lenient towards "the partner with whom the Union citizen has a durable relationship" (article 3.2(b)).
If nothing else, there's the fact that if the two of you actually wanted to move permanently to a Schengen state, you could do that perfectly legally simply by marrying in South Africa first and then employing your freedom-of-movement rights. Even if you're not doing that, the fact that you could do it should be a powerful argument that the visa application is not just a ruse for getting her in to stay illegally.
There's no requirement for an onward ticket or concrete booking, as long as you can demonstrate that you have the financial ability to get one.