That 6 months advance demand is illegal under NJ law. I have turned down offers of prepayment due to this.

https://www.state.nj.us/dca/divisions/codes/publications/pdf_lti/t_i_r.pdf

The maximum-security deposit to be collected by the landlord cannot be more than one and one-half times one month’s rent (N.J.S.A. 46:8B-21.2). It can be less. Any additional yearly security deposit increase may not exceed 10% of the current security deposit. A landlord may not charge a pet security deposit if it exceeds one and one-half times one month’s rent when combined with the regular security deposit.

In the case of Brownstone Arms v. Asher, 121 N.J. Super. 401 13 (1972), and Reilly v. Weiss, 406 N.J. Super. 71 (2009), the courts determined that advanced rents in excess of one and one-half times the monthly rental payment violate the Security Deposit Law. Therefore, any prepaid funds held to secure future rents are considered to be a part of the security deposit. This includes the last month’s rent. It does not matter how the prepaid funds are labeled. The landlord may only require one and one-half times the tenant’s monthly rent as security and the first month’s rent at the inception of the lease. That means the landlord may not require more than two and one-half times the monthly rent at the inception of the lease, this includes the security deposit and the first month’s rent.