Hi will007,
I regularly take my 11 year old boys up with my Miniplane top 80 and Dudek Orca 2 wing (42m3). It was easy when they were younger (8yrs), but now as they're growing I feel it's safer that I get more power, to get away from the ground sooner. (That's what I told the Mrs, and the result is a new Nitro 200)
I'm also 82kg and have taken the Mrs up but that was using a Pap ros 125. It had enough thrust but it would have been nicer/safer if I had more.
The Nitro should be plenty.
One of the most experienced guys I know doing tandems is Clive Mason. I'm sure he'd help you out.
Kind regards
Jamie