@Wally Happy to follow up here! I got your question over to my advanced technical team to ensure I was getting the right information on this specific type of situation. If you have the devices set not to detect or record motion through a Disarm Mode and also do not enable the Snapshot feature, then the bandwidth usage from the devices simply being online would be negligible. Therefore, in theory, this may work out for you. They will still need to transmit some data in order to stay online, but it shouldn’t take up too much bandwidth for when you’re using the internet otherwise.
In all, this could work for you! I will say again that if you’re getting 3Mpbs download and upload, then you will fall in the middle of what we require and what is recommended, as you will have two devices and need 2 Mpbs download and upload as the requirement and then 4 Mpbs download and upload to have optimal performance. You can learn more about how having a poor connection may affect your devices, by giving it a high RSSI value, in our Community post here. Hope this information is helpful to you!