Personal online search/shoper

I'm a full time VanLifer. I would like to put 4 security camera's around the 4 sides of the van, (but I can't put them on the outside of the van because the profile for weatherproof cameras are way to big). I figure the best way is to get 4 low profile camera's that do not require weather proofing. & I can stick them between the curtains and the window inside. Also, they MUST not require the internet (since I don't have much data or am often in area's without data). My camera needs are: 1. low profile (flat) 2. no internet requirement. 3. there must be a way to make all 4 camera's visible on 1 tablet (either split screen or quick access to all 4, like swiping. I presume some app for the cameras) I can think of 3 ways to do this, let me know if you know of any others. 3a:bluetooth. I think the tablet could accept the bluetooth of the camera's if they had that capability? (and if there's an app that is compatible with the camera's? 3b:basic router, not connected to the internet, but powered, and creating a wireles network for the tablet & camera's to use (I THINK this is best right?) 3c. Use my verizon phone hotspot as a network for the 5 devices? (not sure if that uses data, kills my phone, etc, but it doesn't sounds like a good idea to me. 3d. if you have a better idea. 4. night vision (optional)/(I think IR won't work because the glass will block it) I can't find this, and I want to pay someone to locate it for purchase. Depending on how this goes, I'm sure I will have other work down the line, shopping (mostly for vehicle/RV parts/etc...