Does the manufacturer say these are safe for indoor use without the use of an alarm? I know they are rated for indoor use and I would definitely use an alarm myself. Just curious if anyone knows for sure if they release toxic fumes.
Is there much condensation overnight? Either with a vent in the room or not?
They theoretically do not release toxic fumes, due to the inclusion of an Oxygen Depletion Sensor that would shut the unit off before it could start to produce CO or reduce O2 to inadequate levels. So what you do is make sure you have enough ventilation (a couple of square inches per 1000 BTUs) to provide the make-up oxygen. For the Wave 3, that would mean leaving a window uncovered a little bit, though a tent trailer probably leaks enough air anyway.
I personally believe the bigger problem with catalytic heaters is the really hot surface that could cause burns and scorch (and maybe set on fire) fabrics and so on, more than poison gas problems. It would take ignoring the ventilation requirements and a having defective ODS to kill yourself, though somehow, somewhere, someone will manage it. They are, however, a fine heating system, being quiet, effective and with very low current use.
They will put water into the tent. That's an advantage to a vented heater. But the amount is not usually excessive, and coping with the condensation from the family's breathing may be a bigger issue.