Hi Ron,
First, let me send a quick note to Gary (Garmp), since we've pretty much used his thread for everything but to address his original topic!
Gary, I still have no personal experience with the Togo, but I did recently run across one user that had positive comments about it. I don't know if you have seen any of the Robert Morales ("Traveling Robert") output on YouTube, but he's an experienced RV'r--especially in technology issues. In one of his recent videos he commented on adding the Togo Roadlink package to his trailer some time ago. According to his comments, he likes it--here is his reply to a viewer's question: "The Togo works great. It doesn't always work, but when it does which is 90% of the time it is rock solid. It has a booster too so sometimes it will lock to a signal where your phone won't." In another comment, he mentioned that he previously used the Wilson weBoost system to amplify his signal for data, but since installing the Togo system rarely uses the weBoost anymore--only occasionally when he needs to boost signal for his cell phone. Don't know whether that helps your decision, but Robert is an experienced guy that tells it like it is, and sounds like he is pretty satisfied with the Togo.
Ron, I'll try to address your questions, but I'm no expert on these issues--to make a major change like you're contemplating, you'll want to make sure you've got all the individual questions locked down solid. As far as the Netgear Nighthawk hotspot--I haven't had occasion to use it in my home, but mobile performance has been excellent for me; like any cell-based signal it is always going to be dependent on cell signal quality of course (there are antenna kits for the Nighthawk for home use if needed). OTR Mobile uses AT&T, but you can get Nighthawk units for all major carriers. A battery charge lasts about 24 hours with pretty steady use; it comes with a 120-volt charger, and I did leave mine plugged in at times while using, although when fully charged the screen will say to "disconnect from charging". I don't know whether leaving plugged in over the long term will impact the battery. I do know that some users that had constant heavy data use (with multiple users pulling data) removed the battery and just ran it plugged in to 120V to reduce heat build up and over-temp codes from the steady heavy battery charge--so it will work that way.
As far as OTR Mobile data goes, they sell it to folks for home use that are out of reach of cable/DSL as a superior alternative to dial-up or satellite data. Again, it is going to be dependent on a decent cell signal, but I had no impact from data speed with either computer or TV usage, and I haven't seen much negative feedback anywhere--seems that pretty much everyone using it likes the experience. There are other data resellers that also offer truly unlimited data--but my sense from what I've seen is that it may be more expensive.
One issue you'll need to investigate closely for TV use is the policies of the television signal provider. I used Hulu because I already had a monthly subscription to their regular video streaming service, and adding the "Live TV" (for $45/month) was as simple as clicking an online change to my account. It is something that I can add or drop on a month by month basis. However, to prevent multiple users in multiple places at the same time (you, your cousin, your cousin's brother-in-law, etc) from using the service on a single account, their policy is that you must have a "home network" that will stream their service. The way they state it is: "Your Home network must be a residential, non-mobile internet connection. Please note, a mobile hotspot does not qualify as a non-mobile internet connection and therefore cannot be used as a Home network." As long as you have a "home network" that you access at least once every 30 days, you can use a mobile internet connection anywhere in the USA over the same period. This policy would seem to prevent Hulu from being a viable service for live television streaming for you as you envision. It might be worth actually discussing the issue with them however, to see if there is a work around, since they do want subscribers and you're not trying to game their system--you just want to access it at home (and occasionally away) with a mobile connection. In addition, I know there are numerous other sources for live streaming television, and some may not have similar policies against a mobile device being the primary access point.
Maybe some of our other forum members have wider experience with this issue and can offer more advice. From my perspective, the bottom line is that if you can solve the live TV signal provider issue, and have a reasonable AT&T cell signal, I see no reason why your approach won't work. You just want to ensure you have the loose ends nailed down before you pull the trigger.
All the best, Mike