The only conditions of ceding control I would have are that SL admin (now regional) have absolute control over:
agriculture, forestry and fisheries, education and training, environment, health and social services, housing, law and order, local government, sport and the arts, tourism and economic development, transport, social security, immigration, employment, broadcasting, trade and industry, energy, consumer rights, data protection.
Along with this an independent central bank free from xamar control.
In terms of defence; the right to maintain a large and viable national guard, with air and naval capabilities (in case you get any 80's ideas)
And parliamententary approval (which should obv be representative in terms of population) for treatises and declaration of wars.
If that's special consideration then so be it.