Conversion from wheels to foundation is simple. In most places six piers constitute a foundation. There is standard hardware in the modular/manufactured housing industry for this conversion. Place your piers in locations that will allow you to support the main frame members of your trailer and hopefully still be able to roll your trailer off the foundation in the future. Jack it up, install the hardware, remove the wheels and lower it onto the foundation piers. Seal the tires away from light and ozone, you might be able to use them again. Some jurisdictions may require you to skirt the perimeter but that is not structural and can be held in place with pressure-treated wood buried into the soil. Now utilities. Hopefully you can connect by extending the existing utilities on the property, new connections to the mains can include a hefty connection fee. Submit sketches of the proposed layout, get approvals, have the work done by a licensed contractor and inspected.