My last 2 TT's were mostly DC powered for everything except the microwave and Air Conditioner so I only used a 400 Watt pure sine inverter in the bedroom primarily to power my ASV type bipap machine. It worked fine even if I chose to run the humidifier. It's a 28vdc machine and I never bothered to get a DC adapter for it as I already had the inverter. The Bipap I had prior to this one worked on 12vdc so I just direct plugged it into a DC plug I installed in the bedroom.
I wired a 600 Watt Pure sine inverter into my current 5er auto transfer switched to power the whole trailer. I currently have to remember to turn off the circuit breaker for the DC converter before I turn the inverter on, but will wire in a relay to automatically isolate that circuit when it gets cool enough I feel like crawling into the equipment bay area. I also switch the fridge to gas and the water heater as well. My 600 watt inverter powers the TV's, microwave vent fan if needed, my powered recliners etc but isn't big enough for the microwave, AC, or any heating items bigger than our crock pot. It also powers my Bipap through the night no problems.