@LW Thanks for reaching out!
While I have not had direct experience with Rightline Bags I have used many soft sided car top cargo carriers. You are correct that there should be enough play in the bag that will it accommodate your tent. You will want to bear in mind that you will lose a little bit of space around your tent in the car top bag so be mindful of what else you are planning on putting in there. They perform best when they are filled and able to hold their shape so lightweight items like clothes and sleeping bags are a good idea (always in a waterproof barrier like a trash bag or dry sack for extra protection from water!). Additionally, depending on the style of tent, you could remove the fly from the tent bag to gain some space and use it to fill the extra space in the Rightline Bag.
I hope this helps, best of luck!
John
At REI, we believe time outside is fundamental to a life well lived.
