Only way to pay $250 order fee is credit card. Only way to pay down payment is certified check or ACH on delivery day, or ACH (or Plaid) a couple days prior to delivery day through the mobile app. The financing must already be in place, or you can provide proof of your 3rd party finance is in place (copy of check to Fremont and FedEx tracking number will suffice for DCU, for example.) but since your 3rd party finance can FedEx overnight this payment to Fremont, Tesla will already see you paid prior to delivery day so you have no issues.