I am looking at heaters for the Phoenix slide-in pop-up shell model that is currently being built for my Tacoma. I am looking for a lightweight and portable option, so I do not need to lug it around in the heat of the summer. Does anybody have experience with Mr. Heater products? I am wondering if the Little Buddy would be sufficient to heat up the small space of my camper on occasion. Any opinions of Little Buddy vs. Portable Buddy vs. Big Buddy?...or any other brands/models out there?