Almost anything made out of metal can be fixed, modified or fabricated. What it will cost to add the windows, will depend on who you select to do the work, and the costs for the products that you choose to include. Windows are $XXX each and the cost of your local labour pool is $XXX per hour. You will have to take the trailer to a repairing dealer or fabricator for estimates. There is no way you can get an accurate bid on line. Anyone trying to offer one, will be drastically over charging you.

Gard