Welcome Sarah.
I think it's a GREAT idea that you're renting a trailer before buying. We did the same and it gave us some real understanding of what trailer ownership and use requires and what we wanted/needed when we were ready to buy.
You can probably get more in a hybrid versus a hard sided trailer with respect to what your current tow vehicle can handle. We owned a KZ E204S (slightly large then the 196S). We had it for six years and it was a great trailer. Usually it was just the two of us but we did make some trips with up to four people. It gets a little cramped but we managed. I think you're going to find having five people in a trailer of that size is going to be a tight fit.