Your tow vehicle is another issue, about the floor plan.
We searched for over 10 years looking for a camper that had 100% accessibility to everything with the slides in, it was that important to us. Until we found the one, we held on to a trailer with no slides. For us, it WAS that important!
We wanted the ability to use the camper any time, any where, under any circumstances. Now granted we have plenty of parking space at home, slides are absolutely no issue, but we also wanted complete access when we stopped at rest areas, or just needed to stretch out and rest a while when on the road.
Now granted, it's a little tight when both slides are "in" in the rear living room, but still, every cabinet (except one under the sink area) is accessible with everything pulled in.
I have always advocated on these forums for buyers, especially new buyers to spend time in their potential camper, with slides out and slides in. And ask yourself how long you could stay in the camper with slides in. Sometimes it takes a couple hours to figure this out.
I personally think you'll be VERY unhappy if you cannot access everything. You will find it very enjoyable to stop at a rest stop, or a city or county park on your way and go into the camper and fix a lunch, take a break, and even take a short nap.
When traveling (on the road), we will stop at a restaurant , like a McDonalds. One of us will go inside and get the food while the other will stay at the trailer. We'll pull the awning out (in the parking lot), grab 2 folding chairs, and a folding table and have lunch. When done, close everything up. Because we have a dog, we don't have to leave him by himself, as it's usually too hot in the camper and in the truck to leave him. It's fun being able to stop, do thing like this. But it all needs to be accessible.
I suggest you go back to the dealership and talk with them. And I agree, those middle islands do block everything. They are nice when the slide is open, but when close up, you don't have access.
Make sure you can access the refrigerator and stove, bathroom, and all beds with all slides in.
Renegotiate with the dealer. If he want's your business, he'll work with you.
YES, it's a VERY big deal for me!