I don't have experience with the TravlFi product.
We have extensively used a "MOFI5500-5GXeLTE" LTE modem/router combo in our travels. This is an excellent product and an excellent solution for roaming WiFi, as long as you have LTE service. It is fairly expensive, but it is a top-of-class piece of hardware and the software is very robust.
I was just in a location where I couldn't make reliable calls with my cell phone, but the Mofi router was able to let us use Internet and even stream a movie one night. We use a DC barrel jack adapter that connects to a 12v jack on the other end, so I can plug the device in to any existing 12v jack, including my truck (which is always hot and has two AGM batteries). Or just use an inverter with the wall plug.
It's a great solution, and you can even extend the antenna with other products, but I just use the built in 4-antenna solution, which is pretty effective. The best thing is that I have been using it for home internet when at the residence, and take it on the road when we travel... so the same monthly plan is my all around Internet solution. You can certainly get well over 75 Mbps in many Verizon areas, and in many remote US Forest Service or BLM campsites I use, I can still get 5-15 Mbps.
Usually, I put it on the roof outside for best service, but it works great inside the travel trailer and inside the truck cab too. Incidentally, I forgot and left it outside in the heavy rain one night a long time ago, and it has never stopped working the same as brand new to this day. I don't recommend this however, haha.