Traveling by car with a curious cat?

Hello cat forum! I have a predicament that I'd love to hear if anyone has a solution to.

I have 2 cats, one of which that I rescued just recently. My first cat is a mellow 5 year old boy who takes traveling in stride; I have lost count of how many times he has been on a plane and he is fine traveling in cars as well. He is happy to sit in his carrier and just lounge or fall asleep. Even if the carrier is opened, he will often opt to stay inside the carrier. He's pretty well traveled for a cat; he has been to 5 states and 3 national parks. 

My new rescue girl is is a 7 year old bengal. I am introducing her to harness training. She's a pretty typical bengal for all you bengal owners, she is curious and wants to know what you're doing all the time. She is open to car traveling, she tolerates it and she doesn't panic. She will cry in the carrier in the car, but will stop crying if I let her out. She likes to look out the window. I am stuck with this part! I know this isn't safe but I want her to be able to satisfy her natural curiosity. I am making a road trip soon, in May, which will be relatively long and I know she will not like to be locked in the carrier for hours and hours.

How to I make it safe for her to be out of her carrier? I've seen those dog hammock-like things that take up the back seat, but I want to be certain that she is safe. Have any of you experienced this dilemma or have any tips? I will have no passengers on this trip so space isn't an issue. I drive a Subaru wagon with plenty of room in the back as well.

Thanks in advance!

https://www.chewy.com/solvit-pupzip...R1XYQICJX_PF4zAfXD5-gaAoNo8P8HAQ&gclsrc=aw.ds

Wouldn't be 100% secure but would be tethered to a certain area in the vehicle with something like this. We usually have two people when Tom's in his harness so I just keep the leash in my hand. Sometimes he looks out the window and meows nervously at the cars on the freeway and sometimes he stays laid down in my lap. Other times he's trying to go lay down into the floor board. He gets tons less carsick when he's not in the carrier either.

Wow, that's brilliant! Thank you so much! I think I'm going to get that and pair it with this: 
I'll do a few test runs to see if that may work, otherwise I might just get a different carrier that is larger and is open on all sides and see if that helps her too. My first cat Nico is fine with the privacy flaps down on his Sherpa lined carrier, but Hemlock is definitely much more interested in what's going on outside. Nico has been content to sleep in his carrier during any kind of travel for hours. 

When I had to travel across Europe with my then 5 cats, I put them in dog crates, so they could look out. That worked very well.