No segments, no lynx_load(). If you are using cc65 you can use the option -C lynx-bll,cfg. It will create everything into one binary with the extension .o that can be loaded over ComLynx or opened in emulators.
The point is: don't use your own cfg file at all. There is a stock cfg file called lynx.cfg that will build a cart. and lynx-bll.cfg that builds a single binary.