I finally acquired all (well, most) of the ingredients for vegan twinkies. I couldn't find barley malt powder for the inside so I bought marshmallow creme and figured they'd be semi-vegan. It turns out I bought ricemellow creme, so they're completely vegan after all.
I don't think they taste very much like real twinkies, but it's been ages since I had one. They got a thumbs up from Niels and Erik so I suppose it doesn't matter, neither of them have ever had a Twinkie.
The real test will be a friend of mine who was appalled that Erik hadn't ever had a Twinkie. I'm sure he remembers what they are supposed to taste like. I'm going to drop one off to him tomorrow.