When I browsed through Tintin's facebook albums, I saw an album called Tintinville (if I wasn't wrong), and it was about an entrepreneur team went to a place, looking for potential site for Tintinville. If you ask what is Tintinville, well, it was a planned Tintin-themed amusement park. There were planned to be based by Tintin in America, which means it'll have saloon, ranch, sheriff house. It would also have go-kart racing track,swimming pool, tennis courts and an Inn for accommodation. It turned out that it had operated for a while, until it finally closed down (not really sure why, a flop perhaps?).Here's the link to the album "Tintinville"
. I am sorry if the link won't open. (To moderator : I do sorry if it is not allowed)
Anyway, about making Tintin-themed park, I don't think it goes against Hergé's wishes on Tintin. If this was once happened, I think it can be happened aagain (sure there are lots of technical consideration, including fans' demand, but the point is, it's just okay to build a Tintin-themed park).
But I think, instead of a Tintinland, why not a Tintin festival? But make it like Oktoberfest so there wouldn't only be food/comic/merchandise booths, but also amusing rides! (But when I mean make it like an Oktoberfest, I don't mean that it must be overflowed with beers and other booze, I just say make the festival arrangement like Oktoberfest). And don't hold it just in one place, hold it in different places in different periods!(Say, like the first festival held in Brussels, and then the next festival held in Australia, and then the next festival in the next country and so on).