East Lindsey District Council wants to remove vans more than 25 years old from the site as part of their commitment to investing in and improving Kingfisher Caravan Park.
This follows a dispute which began in 2017, when ELDC was seeking removal of vans "more than 15 years old".
ELDC say they introduced a 20-year policy in 2019 and have since offered annual reviews of the vans up tp 25 years.
However, already an estimated 300 caravans have moved off site leaving empty spaces and, according to campaigners, losing the authority more than "£1million a year" in ground rents.
Stuart Allen, who is representing a group of van owners who are affected, says court proceedings should have halted any action by the authority to remove vans until a court decision is made, which could take 18 months.
However, concern is growing by owners of vans over 25 years old because they are still waiting for renewal forms to allow them to stay on site after December 31.
Mr Allen says it is "unacceptable to leave people in limbo worried for their possessions and their future" and has shared a letter from the group which has been sent to ELDC. It states: "Despite several attempts at calling you and emails from solicitors and myself any form of response appears to be sadly lacking.
"At present Court proceedings are in place with the Council over Kingfisher Caravan Park changes and the listed people have agreed to pay site rents until this is resolved.
"Unfortunately a few of the group with caravans over 25 years have not received a renewal application form and when they contact the office they are told their caravan will be removed by the end of the year - plus the office is still waiting for the letter from you to send out (after the site has closed)."
Mr Allen says they are calling on the council to confirm they will "abide by the court process and allow these people to continue to use their caravans on site (after paying the ground rent) until the Courts make a final decision".
The Standard has requested a response from East Lindsey District Council about the matter.