Run a Tunnel on existing Comcast cable?

Comcast has wired our farm so that we have two taps coming off of the telephone pole. One runs to the barn and one runs to the house. While we need WiFi access in the barn to handle security camera feeds, we don’t need the bandwidth afforded by 2 taps. We also don’t want to pay for two internet subscriptions.

Electrically, the two taps configuration is the cleanest. When I spoke to the Comcast engineer, he said that there was not electrical continuity between the taps, suggesting that they have active HW on the telephone pole driving each tap. If I tee one tap and put two terminations on it, the signal theory says that there will be reflections off of the tee and each of the taps making the line more noisy. However, I know that you can put two cable modems on one cable, for example (See: https://forums.xfinity.com/t5/Your-Home-Network/Using-two-2-internet-cable-modems-on-a-single-service-line/td-p/3297233). What I want is slightly different:

Can I take the signal from one tap, tee it at the bottom of the telephone pole and connect it to the wire to the barn and wire to the house. (distance from house to pole is 250ft; distance from barn to pole is 250ft; Comcast HW is at top of pole; tee would be at bottom of pole)

Then, in the barn I want to put an access point with a tunnel setup to a corresponding device in the house. Finally, in the house I would put the comcast access point and have the tunnel set up to route any outgoing traffic to the comcast access point.

Please note that I am aware of other solutions to this problem:

1. I tried power line modems — they were too finicky/unreliable for the distances involved;
2. I tried Ubiquity line of sight — the distances, bricks walls, trees, and weather combine to make this unreliable.

UPDATE:

As I have considered this more, I’ve been thinking of it like the LAN in my house. It can have multiple routers, multiple DHCP servers, multiple connections to the internet (see, for example: https://www.mushroomnetworks.com/blog/should-you-migrate-your-2-router-2-isp-network-to-a-multi-wan-router-network/). The topology I describe would be reasonable/valid assuming I put a bridge at the point where the cable splits to house and barn.

Since Cable seemed to allow multiple devices on a single wire (is this in fact true? I thought I sited a reference where this was happening), I was hoping people would know of devices that would allow me to do with cable what I could do with my home network.