Ok first...you need to understand a few things.
1. Your "HOTSPOT" is a stand alone receiver; for better, or for worse. So, it's internal antenna, location, cellular modem will all be the KEY factor to how well you pull in an internet signal.
2. As with many things, GARBAGE IN - GARBAGE OUT. So, if your "source" is crap (ie. hotspot, CG wifi, Cellular, etc.)..ain't nothing the Pepwave can do to improve it.
3. There IS NO "Wi-Fi as WAN" port on the Pepwave Transit. That is an ethernet port that is labeled WAN, which is for a dedicated source to be plugged into your Transit. This could come from another modem/router, a CG Fiber-Optic feed (some have it!), etc.
So now, your issue of "TV" on your wife's "data". LOL. WELL...you say nothing about how much data is on that card's plan. You also don't say what she does for data. So, don't try to get me in the middle of your marital bliss! LOL
That said, my "guess" as an expert (more than 50 miles away), is you won't drill through enough data watching TV to make a blemish on her data allotment.
Just establish that Network with the Pepwave, and let it do it's magic. You ask about it broadcasting outside your RV? OF COURSE IT WILL!!!! Do you think those little airwave thingies will stop at your door? ;-) The Pepwaves, EVEN WITH THE STOCK ANTENNAS, are strong enough to send a signal across a LARGE campground!!!
enjoy!!