I don't follow that the word 'control' makes the nominee method unconstitutional unless you mean it is the agreements that some notaries attach that 'appears' to give control to the foreigner.
That's what I was driving at - the possibility of a future challenge to the nominee agreement, which is the weak link in the chain of land use rights. Courts invariably give greater weight to constitutional law in disputes.
While it might seem negative, it is sometimes good to consider all eventualities in order to protect yourself. For example, I would tend to trust a close family member too, but I would personally want to cover myself in the even of something happening to that family member. How would *his* immediate family react should they find themselves suddenly 'inheriting' your property? It is theirs by title; would they feel bound by any private, quasi-legal agreement between you and your nephew?
One legal way out of this impasse is to lease. Both parties to a long-term lease (unlike a foreigner "purchase" agreement) are fully legally protected. Typically a lease would run for 20-25 years, after which it can be renewed. In some ways it is similar to the ACT in Australia, where no-one can actually buy property - they lease it from the government.
Maybe it would be possible for you to execute a long-term lease with your nephew (since he is the legal owner of the property) which would give you both security of tenure and a great deal of flexibility in terms of renovations etc. Since you have already paid for the property, it makes sense that any payment for a lease term be purely nominal - a 'peppercorn' rental, so to speak.
I stress that these are just my opinions - consulting a trustworthy notaris for advice, and to draw up the proper documents is, of course, essential.
As a postscript, I see that the Thai government (which has similar laws re foreigner property ownership to Indonesia) has just cracked down on nominee arrangements there. They are threatening to seize and sell all property bought 'illegally' in this manner, and to deport foreign owners for various property law breaches. Whether this is posturing or not remains to be seen. I would imagine, however, that Jakarta, with the current nationalistic fervour sweeping the country, would be looking very carefully at the Thai initiative to see whether they could reap a financial benefit as well ;-)