Thanks to the help of many people here, I've put together a fast and reliable system for running WordPerfect for DOS under DOSBox. (Details here:
http://www.columbia.edu/~em36/wpdos/wpdosbox64.html.
The user must supply the copyrighted WordPerfect program files.)

One problem that I haven't been able to solve is this:

WordPerfect has text and graphic modes. If the user has set the graphic mode screen size to be larger than the actual size of the monitor, then DOSBox (or at least my build) crashes when the user tries to switch to full-screen mode by pressing Alt-Enter. My guess - it's only a guess of course - that this is a bug is SDL.

Is there a patch available that would compare the desired screen size to the actual monitor size, and if the screen size is larger, then DOSBox would ignore the attempt to go to full-screen mode? That would certainly be better than crashing.

If this already exists, but I simply haven't found it, I apologize for wasting bandwidth. I'll be very grateful for any help.