Like I said, just because you can doesn't mean you should, it did says 28mm max.
Hence the recommendation of the Rigida Grizzly with it's 19mm internal width that allow you to run your 28mm tyres at the ideas pressure.
Hubs?
Your suggestion of the 105 hubs is more than enough for the purpose, if you want cheaper, the Tiagra is equally as good for a little over half the price of the 105.
Like I said, just because you can doesn't mean you should, it did says 28mm max.
Hence the recommendation of the Rigida Grizzly with it's 19mm internal width that allow you to run your 28mm tyres at the ideas pressure.
Your suggestion of the 105 hubs is more than enough for the purpose, if you want cheaper, the Tiagra is equally as good for a little over half the price of the 105.