If the rig has a Crestron system, then cost is not an issue. He overpaid on the control system
Run WIRED. And ideally to the trailer as well. There are plenty of connectors for this purpose.
WiFi, even when installed with great hardware has a limited bandwidth. And this is the exact same bandwidth as what your Phone / Tablets / Laptops will want to use. And Video is the largest consumer of that bandwidth.
You would run all cameras wired to an NVR (networked video recorder) and then the output of that would be an IP connection to the Rig's ethernet network. The Rigs WiFi access point would also be connected. The Tablets typically would be connected WiFi.
On the topic of NVR, on a higher end install, that would typically be a 360 view of the RVs cameras where the images are spliced together in software. That reduces the number of NVRs that could be used as not many support 360.
You could also use a 360 NVR for the rig, feeding a more standard NVR for recording and playback. The second NVR could serve the interior of the trailer / RV cameras. The Crestron system would manage which view goes to which device which is then presented to the user's tablet.
But, the data traffic is between the camera(s) and the NVR that is NOT on wifi (if wired). The Wifi is affected only when the tablet is viewing the NVR output which is only one screen of video (even if multiple camera mini views are shown on that one screen).
You would also ideally be controlling the NVR from the Crestron system. That will require the Crestron dealer to program and a compatible NVR. So, talk to the Crestron dealer on all this before making a decision on approach and brands. The cameras need to be compatible with the NVR (especially if the cameras are IP and not analog).
The output of the NVR: This can be h.264, h.265 or mjpeg...the display device (tablets?) would have to have the software to render (playback) that type of stream. If the video is to be meshed within a Crestron user interface, then the Crestron dealer has to be involved with these decisions.
For our control system this is how I would wire:
Analog cameras (Front, sides Rear) of RV hard wired to a 360 NVR. The analog 360 output as an input to an Exacvision NVR. IP camera on back of trailer, interior of trailer, interior of RV ethernet (hard wired) to Exacvision. Exacvision sending MJPEG to the control system user interface (browser). So the Exacvision would have one analog input card and ethernet (which is why that specific NVR is being considered as most all don't have that flexibility).
The control system at a minimum could control the 360 NVR via IR (not great) and IP control the Exacvision (a pro solution).
The Exacvision would be on the ethernet network managed switch. So would the automation controller. The IR would be a GlobalCache IP2IR device also on the ethernet and hard wired IR emitter stuck to the 360 NVR.
The user interface would have a view of all cameras, when clicking one of the mini pictures would go full screen to that camera of interest, and navigation buttons to put the system into 360 view vs. Interior of RV vs. Interior of Trailer vs. Rear View. All of this user interface would be within the larger control system user interface to manage all media and lighting, and HVAC and RV systems.
Do it right. If the above is gibberish to you, hire a pro.