Although we live in AZ, we do without. Lack of humidity here helps, but mainly, we go where it's temperate - mountains or beaches in summer, deserts in winter. Grew up in MD, though, so I understand your desire for AC!
I'm thinking your 1994 is probably not reinforced for a roof mount, so
window or closet.
Saw this earlier today:
A/C Window Mount Design for Scamps
Has the advantage of simplicity, but has to be set up and taken down every time you move the trailer.
A closet installation is a lot more work and requires cutting a hole in the shell, but many have done it. In fact, at one time it was the way Scamp
did it at the factory. Do a Google search on this site for "Scamp closet AC" and you should get some ideas.