Panels help ensure you are visiting the cameras less. I think they more than pay for themselves. Your panels would pay for themselves even faster with all of your links.
As far as cell signal is concerned, we have almost zero cell service on two of the farms I run Cuddelink systems. I just placed the cell camera in an area that I periodically get 1 bar of reception through LTE. That is enough for the K-series cell cams I have running as my home units. About twice a year the camera loses connection to the network and it needs to be re-established at the camera. Coincidentally, these seems to happen in the late spring or summer more than any other time of the year, so it hasn't been a big deal.