Fences are allowed.
To make it easy I'm going to go ahead and say that subways are banned period. For real estate you can build but a register of any kind or a subway cannot be placed ever. Also adding that EA/UC lots with subways and registers other than consignment are also banned from being placed.
If a specific Sim gets stuck you can reset them but a blanket reset is only allowed at 4 am. To use resetSim, we're talking the Sim can't move or be directed to do a single action without it cancelling type stuck.
Edit to add: This challenge is about getting as many skills and skill challenges as possible without any skill boosting or tricks while still having to pee, eat, sleep, talk to someone, take a shower and have a good time. If you can think of a trick to get out of doing those needs or a skill boost, bring it to our attention because it needs to be removed as a possibility.