The only trailer I personally own and have insurance on is a 28 foot enclosed. Not to be nosey, but I can’t imagine you sold your porsche for less then 60-70k and I wouldn’t want to be liable for shipping it open air for 1800 miles. I would guess my cost for the trip would be approx. $2000 and that is just fuel, hotel and food. I’m not sure what your buyer is planning on paying though. I would probably be around 3,000. I would need zip codes for pick up and delivery to give you an exact figure.