Just switched my order from a sequoia to a tundra

I just ordered a tundra hybrid limited today with air suspension. The truck will be towing a 7.5 x 18 cargo trailer that I will be converting to a mobile office / motorcycle hauler. I'm thinking that the trailer will be 6000+lb so I wanted to get the air suspension.

If I were to get this option on the new Sequoia, I'll have to step up from the Limited to the Platinum model which is rediculously expensive. Given that there is no allocated vehicle yet anyway, the dealer agreed to switch up the order to a tundra.

Since the Tundra is relatively cheaper, I am leaning towards keeping the 4R!

Now I need to get a custom topper. Given that I'm giving up the 3rd row to get more towing capability, I'm thinking of building a platform for my dog in the truck bed. I am looking for a topper option that will allow for me to roll down the rear window and have access to my pup.

I'll keep searching but if you have any ideas or have seen solutions, please let me know.