I'll bite. Unless I mistake the purpose of the thread, here's my (barebones and somewhat disorganized) stab at a simple constitution to get things going, with an eye toward decentralization relative to the U.S system.
Local
Local government is divided into counties, as in the United States. Each county is led by 3 directly elected councilors, who have the power to appoint people to administrative positions below them (but only to tasks related to their office) in order to run the county more effectively. All three councilmen can propose laws relating to their county, but only if they don't conflict with regional law. Councilors can propose new laws, or they can be proposed directly via petition. Laws proposed by petition must have the signature of at least 10% of the county's people, to a maximum of 20,000, before they can be put to popular ballot. Laws proposed by councilors must be approved by at least one other councilor before being put to popular ballot. All bills on the local level must have at least a 3/5 majority to pass.
One councilman is the Mayor, who has the power to appoint local judges and school officials. The mayor is ultimately responsible for the issuing of licenses, and manages the census and other data. The second is the Treasurer, who manages county finances and the collection of taxes. The third is the Commissioner, who is responsible for the management of elections and appoints law enforcement. Any elected or appointed position is open for recall, under the same rules as any other bill.
New counties can be formed by initiative, but must have a minimum area and population (no idea how much) to prevent exploitation of the regional government system enumerated below.
Regional
The regional government is the highest authority in the government, and can be thought of as analogous to U.S states in that each region contains many counties. Regions are more fluid, however, and while each region must be geographically contiguous, counties are free to leave it and join any other. This proposal must win a 3/5 vote of the regional electors regardless of circumstance. Counties may form new regions, but must be able to convince at least 4 other geographically contiguous counties to join their new region.
Regional electors are essentially analogous to U.S representatives. Each region chooses one elector for every 5 counties it contains, with the difference being rounded up. Electors are elected directly by residents of those 5 counties. These regional electors are dispatched to serve on the Council of Regions, which mirrors local government in its structure.
The electors choose a Speaker and a Treasurer from among themselves, and select a marshal from a list of suitable candidates. Unlike the county elections, bills here need only a simple majority to pass and can be proposed by any member of the council, but they can be vetoed by the Speaker. A bill must have a 3/5 majority to overturn the Speaker's veto. The speaker does not normally vote, and has no special privilege for proposing bills, but will cast the deciding vote in the event of a tie. The Marshal is responsible for the administration of the army, and has final say on tactical decisions, but does not have the power to define overall military objectives. The Treasurer is essentially the same as on the local level, but does not have special powers of proposing bills.