Vented is the only way to go.
Splendide make an excellent combo washer/dryer, but you have to adapt your laundry habits to "the RV combo way". Small loads done more often and do laundry while you do other things rather than waiting on it. Take advantage of the automatic combo cycle by throwing in a small load and going about your day, hiking, sight-seeing, whatever. If you save up a week of laundry to do all at once, you will get frustrated at how slow it is compared to home.