I see Fuji have released their new 1.40 firmware upgrade for the x-t30. It's supposed to support X-Webcam now. I'm not sure if that equates to usb tethering but I'll download it tomorrow and give it a try.
I would like to know if I can take up to 5 multiple exposures on one frame?
Is this possible using the X-T2 or X-T3? Or, is there an alternative fuji camera I could achieve this effect with?
Your comment intrigued me enough that I did some research. Based on the information at http://www.doc-diy.net/photo/remote_pinout/ most Fujifilm cameras use the same "remote protocol" as most Canons (and some Olympus and Pentax). So I wired up a 3.5mm plug the same way and it worked! So all you should need is a cheapish ($10 to $12 on Amazon, like this https://www.amazon.com/Kiwifotos-RS-80N3-Control-Shutter-Connection/dp/B071XPW655/) Canon remote and the plug adapter.
Someone on another thread somewhere said "if you look for Canon Rebel you'll be good".
I overlooked your concern about portrait backgrounds, but I can say I shoot a lot of my grandson's LEGO work. I think this qualifies more as product photography, but there some features of these lenses that one could apply to portraits.
I shoot the LEGO scenes with the XC's because of the close focus. I shoot at 35 mm from about six inches away at f6.4 or f8, with the background about eighteen inches behind the subject, and use flash from overhead. I was surprised to see the background was beautifully blurry, so I would say when these lenses are in a close focus situation, they do real well with the rule of thumb that the distance from lens to subject and subject to background should be four-to-one to get some blur. This doesn't work as well with the XF18-55 because its minimum focus distance requires too large of a product stage to get the four-to-one ratio.
So, I think you can still achieve suitable background blur in a portrait by situating the camera as close as is practical to the subject, and situating the subject at four times that distance to the background.
Well, that was just too many words to say I think you can shoot portraits just fine with XC lenses.