I carry a spare, empty SD card and put that into the trail camera, after taking out the existing card.
A good tip is to always carry spare or at least check the cameras battery levels, when checking the SD cards. Frustrating when the batteries are low, out in the field and you have no new ones.
Regarding viewing the SD card pictures, it can be done a few ways, a suitable laptop or PC, a mobile phone, mobile tablet or via a dedicated SD card viewing monitor.
I use an SD card adapter and can view on my mobile phone or my phone tablet on site
( without the need for putting a new SD card in )
It depends how much you want to spend on additional kit.
An extra card is not essential, but an SD card adapter is,
as it makes viewing camers pictures / videos, easier on a bigger screen in the warm + dry, rather than out in the freezing cold + rain, at the camera site !
SD cards + adapters available from the usual sources, Ebay. Amazon etc.
Good luck, which ever route you choose to go down.
ATB.