I currently have an aluminum open trailer that has worked well as a starter. I am preparing to switch over to a enclosed trailer later this year. My main reason is that I often do 3 day events and want a secure place to keep my tools and car over night along with the ability to put the car into the trailer during bad weather. An enclosed trailer also provides personal shelter from the sun and rain. As far as the car getting dirty when towing, I have not had any issues unless it rained.
2007 Lotus 255 Cup, AP BBK F&R, Innovative mounts, RLS CF Intercooler heat shield, Railer diffuser, Custom hood Pins, gPan, Saikou Michi oil cc, RLS AL Intercooler tubes, Radium FST, 2Bular GT3 8X24, RLS suplemental IC Scoops, APR canards, CF rear wing, CF Scoops, Radium Fuel Rail and AN fuel pump adapter, AN fuel lines, 2bular decat and headers.