While true in general, we already have Falcon Heavy, SpaceX Dragon and if it is just 'make the simplest possible moon mission' and you had the budget, you could

While true in general, we already have Falcon Heavy, SpaceX Dragon and if it is just 'make the simplest possible moon mission' and you had the budget, you could make it happen. However that is not how Congress would do it anyway (NASA can not choice).