you can also connect a 1:1 isolation transformer as a 1:2 step up autotransformer, and it will effectively double its "rating"
so a 1KW isolation transformer will be good for 2kw input and a 1900 watt output is probably realistic.
lol, if you can get it started and synchronized, you could use your 5kw generator as a 2:1 step up.. but you'll probably have to machine a shaft and bearing to support the generator...