If you are considering holding any training in North America, you may consider two additional possibilities:
1. Hold training in Las Vegas, Nevada [IATA: LAS]. Las Vegas is usually the cheapest place (on average) to fly to within North America and MANY options for international flights. Cheap hotels & facilities; at least two training providers I know of have operations there that could scale adequately.
2. Hold training in Canada (typically Toronto [IATA: YYZ]). It's sometimes much easier for Schengen-group citizens (i.e. you!) to enter Canada than the US, and Toronto has facilities as good as anywhere else (not as cheap as Las Vegas, but much cheaper than Europe). I can think of at least four training providers there that would happily rent their facilities to you, and finding servers should not be difficult.
Since you likely do not have servers hidden away somewhere over here, I will point out that Dell, IBM and HP (and probably SuperMicro, but I've never asked them) are likely willing to secure several servers from their demo pool if it gets them exposure. Toronto is Canadian headquarters for all those companies, so their Canadian demo pool is nearby.