Neil, I'm not sure I understand your logic. From what you've stated, your motivation for wanting to have surveillance on your home is that you previously suffered a $20,000 loss for theft and damages and you want to monitor the property in the event something like that might happen again. The cost of a dedicated IP surveillance system even if it is $1200 or more is peanuts when compared to the loss you suffered along with the security and peace of mind it would provide.
Like I've already said, Mobius cameras shooting time lapse photos would not be adequate, would be very expensive in their own right, might fail to work at the critical moment because they are not really meant for this purpose and would be a huge time consuming hassle. You would have to constantly go around and remove all the microSD cards and load the footage on your computer and manually view the clips. You then have to go and put the all the cards back into the cameras which would be in some sort of waterproof cases from what you are saying. You'd have to deal with some sort of separate 12v/5v power supplies. You'd have to format the cards periodically. Dash cameras can not see in the total darkness although some are "reasonably good" in low light. There is the very real possibility that an event could occur but you might not get back to the cameras in time before it writes over the important footage.
A dedicated NVR would give you complete reliability, far better image quality with true 30 fps or more HD video rather than time lapse photos, true infrared "see in total darkness" night time performance and set it and forget it functionality and convenience. The NVR provides you with various ways to review and work with the video footage. You can also go back and forth frame by frame, zoom in to the image or view in slow motion. NVRs can even be programed easily to email you if a certain type of event occurs or trigger an alarm. Beyond that you could monitor your home on your phone, computer or tablet from anywhere in the world. You can record weeks or months of video depending on the size of your hard drive. Etc. etc.
To answer your question about IP cameras being protected from the weather you need to buy dedicated IP surveillance cameras designed for use outdoors. These waterproof cameras are very common and they have built in Infra-Red illuminators (LEDs) that allow the cameras to see in total darkness as much as 100 feet or more away.
Also, think of it this way. Aside from not giving you anywhere near the performance, convenience or reliability of a NVR, 8 Mobius cameras would cost you $552 at 69 dollars each. Eight 64GB microSD cards will cost approximately 40 dollars each, so we'll call it $320. You'll need eight power supplies plus cables (I have no clue what you have in mind for this but hypothetically for the sake of argument let's say you get off cheap and spend 25 bucks for each battery or transformer set-up or whatever. That's another $200. Then there would be the JooVoo waterproof cases (or whatever you come up with) which are about 23 dollars USD, so if you had 8 of those it would be another $184.00. That totals $1256.00!
This is the proverbial no-brainer. It makes no sense to use anything other than a true full time fixed surveillance system for your needs. Dashcams are really a form of "action camera" designed to film scenes in motion for periods of minutes or hours in a moving vehicle. They could be used temporarily for fixed surveillance but they are not intended as full time 24/7 cameras, especially outdoors.
