So, I ended up going with the medium Snoozer Luxury Lookout II. I ordered an extra tether and will be eventually ordering the Paw Rider. I think the large seat would have been too large for my pups and the medium (according to measurements) isn't that much larger than the large Pet Gear seat I have.
I will have to post some pictures of the pups in the convertible when we get it
They are loving riding with the top down!
Thanks Kristin!