G'day & Welcome, to the forum and camper trailers.
It's a good idea to hire first, my first exposure to CTs was a Trackabout that I hired for a trip to Fraser Island. I knew I'd never be happy in a tent again.
Yours wouldn't be the only wife who likes her comforts and doesn't think they're available whilst camping, but you can change this perception. I like to say "that any fool can be uncomfortable", and the camper allows one to take whatever you need to ensure your wife doesn't feel like she's slumming it.
I wouldn't go the cheapie, as this might not achieve the goal above, whereas a good hire unit is a better chance. On the second hand trailer, the issues you mentioned are (relatively) small. How long, how often and how far are you going that you'd absolutely need two gas bottles? A second battery is easily added, but if you're starting on powered sites, it might be a while before you need it. One 100Ah battery will run lights and a fridge for a weekend, or near enough.
