That would certainly be a good start. People moving there because of UBI is expected in general, so it would also yield valuable results in that regard. There's the ethical issue of forcing people to be part of the experiment that really don't want to, even if you give them the option to move.
I don't know whether there are upper limits on local taxes. One of Germany's local funding is business tax ("Gewerbesteuer"), which communities regulate by setting their multiplier, the lower limit is 200% (of the taxation base), with most between 350% and 450%. The highest I know of is 900%.
Property tax also varies between 200% (minimum) and 1800% (according to Wikipedia), so there's some room as well.
Combined with an initial donation, that may be possibl. If it's somewhere where people don't naturally move to (e.g. not a major population center), the moving-effect might be very welcome as well, repopulating the area.