You could always include an option to set up a path to whatever version of DOSBox people want to use (for example, I don't use the standard DOSBox 0.74...I use an alternative fork that allows for state-based saves and some extra graphic filters). Also, include a link to whatever directory FRUA is installed.
Then, just launch that version of DOSBox, pointing to the ckit.exe file in that FRUA directory (where, we assume, the design directory is also located).
Apparently, the command line parameter "dosbox ckit.exe" is all it takes (haven't tested it, mind you, just found it in the documentation). When you run DOSBox this way, if the file you point to is an executable file, it mounts the directory where that file exists as the C: drive, and then runs that program.
Don't know if that helps or not.