I've had toppers on my Chevy/GMC 4wd crew cab trucks for years. I can recommend the ARE "Sportsman" with sliding side windows along with the "windoors" that an earlier poster suggested (the entire side windows lift up for easy access/airflow in the bed). I also agree that on the road, dogs should be in crates. If you put the crates on rubber mats, they don't slide easily. I was in a minor accident on I-90 just east of Chamberlain, SD several years ago and was sure glad my Golden was in a crate; it saved him. I take 2 dogs and there is still enough room for 3 guys' worth of gear, dog food, water etc.