Yes the more wires ( one ) do make it a bit more tricky to install, but at least you don't have to route those wires to the windscreen.
Also you can not bury the main unit too deep, even though it will have wifi and also a screen to do settings on, you will probably want to get to the memory card now and then, and the main unit to do firmware updates and the recommended occasional in camera format of the memory card.
The K2S camera that are dual remote i am testing actually have a option to put it on the windscreen or dashboard, but that just seem silly with all those wires coming off one side of the almost matchbox small main unit.
No way can i see that be done in a nice way, i am not sure if SG will also have this to me silly option on their DR model ?
But the whole point of a dual remote system are to have the main unit out of sight and the sun.
The conventional current dual cameras are fine to work with on the windscreen, it have the GPS mouse antenna on a short wire, so it just need to be routed out to the upper corner of the windscreen ( where i have all my GPS antennas )
Then the unit of course also need power, from the cigarette lighter socket, or the hard wire kit if you want to use parking mode.
And then you have the 1 wire you have to route out back to the remote camera there, thru 1 wire go power to the camera and data back to the main unit on the windscreen.
The current conventional cameras are quite small, have about a creditcard sized footprint on the windscreen, so if you have a dotted area on the top of your windscreen you can have most of the camera on that and just the lens peeking out below the dots ( i have this in my car )
Current wedge type cameras like the SG ones and other, they often come off as some form of sensor on the windscreen, pretty much no matter how it is installed as long as it is in the middle and on the top of the windscreen.
The K2S camera i keep bringing up as it is a DR type camera you can see some pics ASO on here
https://dashcamtalk.com/forum/threads/k2s-received.37896/
The cameras for this make/model are smaller than the remote cameras SG use now and on their DR model, but both are plenty small as is.
There are also a picture of the smaller K2S rear camera Vs the remote rear camera of my SG9663DC.