Give some serious thought how much you like crawling around on your hands and knees. I dislike a topper for this reason alone. Sure, it can seem like a good idea to keep the elements off. But as mentioned it will get too hot in there during the summer. Invest in some weather proof containers for your bed instead.
I transport my dogs in the bed of my truck all winter with the mud river crate covers. They are warm and toasty every time I let them out.
I’m with you on this one.
The other disadvantage to a topper if that it limits what you can haul from a height perspective. Unless you like moving it off and on constantly. No thanks, I’ll stick with the tonneau cover.
I’m personally not really worried about my dog (lab) getting cold. I’m way more paranoid about her getting too warm.