Good question...REALLY good question.
I believe this is the single topic I have never found a satisfying answer to, even after reading books and countless Internet opinions about it.
I think the general rules of thumb such as "2Â½ times main memory" are useless recycled advice from a long time ago.
You CAN run without a pagefile, but some applications really don't like it, so even if you have plenty of RAM I would advice you to have a pagefile anyway.
You could try with a relatively small pagefile such as e.g. 1 GB and se how that works; Windows should tell you if it runs out of virtual memory and has to temporarily expand the pagefile.
Writing/reading random pages from and to a SSD is much faster than with a HDD, so I would suggest using the SSD for paging.