As a lender, we do not lend on flips in the North half of NJ.

Those private companies manage all the maintenance.

The lender plans to finance 80% of the purchase price and 100% of the renovations for my property, which is approximately 3000 square feet, renovation loan amount of around $50,000.

No risk=no reward Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

Many lenders typically require a minimum loan amount of $75,000, allowing you to access up to 75-80% of the property's value, provided that the DSCR ratios meet the lender's requirements. 

I have a lender in first position (75% LTV) the seller will be financing (20% LTV) and I am contributing 5% LTV + closing costs.

Or would the better of the options be to secure private money at $50k for 3-6 months to fund the DP? 

No Trespassing, Private Property, Video Camaras in use...Oh yeah...

The builder will need to be approved by the Bank/Lender or the bank/lender can provide you an already approved builder they have used before in that County.Once the builder is approved the Bank/Lender will have a initial meeting and set up an agreed upon draw phase based on the work that will be completed in phases.Best thing to do is have a conversation with a seasoned Banker or Loan officer to start an application and set up step by step plan.Feel free to reach out if you have any questions I am always happy to help and talk REI.

Unless lender specifically agrees to a subject to transaction, the loan by way of the deed transfer is in default, and as such the lender can accelerate the note demanding full payment at any time.4.