If you are planning on going to Mexico I wouldn't get a newer Sprinter diesel as they need ultra low sulphur diesel which Mexico does not have in most places yet. If you want to have a diesel you need to stay pre 2007 to get one that just runs on low sulphur diesel. The newer ones also require you to add DEF (Diesel Exhaust Fluid) which might be a problem in some remote areas. Again pre 2007 diesels do not require DEF. There are some diesels that didn't require DEF till later. Ram pickups are examples of this.
I agree with a single woman in fact a single male also to travel in Mexico could be putting themselves in harms way. Not saying it is going to happen but it could. There is always safety in numbers. If somebody wants to do harm to you it is always easier to tangle with one person than two.
This is IMO