I have a 15.6 inch, but I use it as a desktop and prefer to have a separate keyboard, as I can put it on my computer table at the right height for typing so as not to damage my shoulders, elbows, wrists, etc. I have the keyboard on the pull-out for keyboards on my computer table. It’s not a good idea to be doing a lot of typing or mousing on a table of regular height. I also have a separate mouse hooked up and, in addition I even hooked up a separate monitor, so I can see things as big as I like. I have it set up as one long screen, but I basically use the separate monitor.
As far as SSD and regular HDs, you can get a relatively small SSD – 125 GB or 250 and have all other memory be external. This is sometimes useful if the computer crashes and you have to send it in to the shop; at least you have all of your main files stored on external memory and can easily access it on a rental or loaner computer.
GL figuring out the details.