Thank you xfiltrate.
Xfiltrate has posted time and agen on how get a bike a ride in South America legal. Helping many pensonly do just that. You may chose a different path than the one he shows you may get away with it. Just remember not every place we ride threw has the safety nets as most of the EU or US or Canada has. Hurting some one out there may mean they live out there life that way there is no just pop off to hospital be out in week right as rain pay nothing. There life may be bit more grim, we ride there we see how some must live. He has posted as a person that lives there and is working with the laws he has. Posting how to get away with things illegally is gray area on the HUBB and at the VARY least looked down upon.

If you want to talk about what can be done in theory well ok. In most cities there are areas that sell forged documents as well as computers that can scan in a document and then it be altered then printed and laminated. Then there is the bribing your way passed and threw any other problem you may have. This being said however the time you will spend in jail will go up with each offence each document you have. You can also gust get a fast bike and not stop but they do have the right to stop you any way they want and they have guns. This is not bribing your way out of a speeding ticket or to get stamps done faster at the border. You are taking away a way some states make money they do not like that. It is up to you It is real world there real nasty jails and real guns.

but on to the to the Qs and As

1) This Question has came up 3 times this year that I know of someone in the Americas no licence and going to take a long ride and wanting to know how to do it. Your Dutch one one will do just fine. If you do not have one well In short really no legal easy way. You can try to get legal help from a lawer and of the Dutch embassy there.
2) get a small bike say a 125 to 250 and ride slow and have a grate time. Take it to xfiltrate pay him to keep it, it will be there when you get back. Or pay the tax on it and give it away, sell it for the tax, do not know if it is true but read some place you can give to the cops and the border guards and get a tax stamp saying you paid.