Okay, that helps Bonnie... now the bad news. It's VERY doubtful your 1977
Scamp was built to hold the
weight of a roof top A/C. Prior to the big
Scamp plant fire in January 2006, trailers had to be ordered to support the
weight. If it wasn't... and probably wasn't, you can't put roof air on top or it will bring the roof down! You can retro fit, by adding braces (either on the outside or interior) that go from the floor across the ceil and to the other side (if done on the interior). Most don't want to go to that extreme unless removing everything from the inside.
Your best bet would be a removable window A/C or an A/C in the closet vented to the outside... or.... all have been accomplished successfully by owners.
Pulling and resealing
windows is easy. Just takes time, a little $$ and once you do it, you'll wonder why you wanted to pay someone!