We used a Wave 8 in our 36' DP for two winters when we were full timing. I can't comment if a Wave 3 is sufficient for your TT or not, but I will pass along my impressions of these devices.
While generally considered safe, propane heaters like the Wave do put off small amounts of CO and other nasty chemicals... some of which smell. You will have lots of moisture released... the candle idea might help some, we left vents open. They also burn oxygen so ventilation is important, especially in a tight fitting RV!
We considered piping the propane from our class A's main propane tank but decided to carry a spare small propane tank for the Wave that sits on the ground outside the rig. It made getting propane easier than taking the whole rig to town when all we needed was portable heater fuel.
We added a long enough fuel line to the Wave in our rig that we could take it outside to start it. That is when the greatest objectionable smells are released in our experience.
These things are rated safe, but I recommend you read this article about these type heaters before you start using one, the information presented is the best I've found anywhere on the subject... Vent Free Heater Cautions