Me too: "I'm wondering how anyone would ever build a bootloadable application if this doesn't fit.".
Our issue with the Bootloadable Component causing a ROM exceeded error was due to erroneously giving the Bootloadable HEX and ELF files instead of the Bootloader HEX and ELF files in the "Configure Bootloadable" Dependencies tab settings.
Is it possible your issue is due to configuring the Bootloadable instead of the Bootloader files as we did?
Have a nice week,