GVP boot68000
Unfortunately no. The BOOT68000 option sets a register to indicate the machine
should reset into 68000 mode, and once in 68000 mode, there is no access to the
accelerator's register to set it again.
There is a jumper that will force the accelerator to "stay out of the system"
and creative users have attached a toggle switch to this jumper allowing them
to turn the accelerator on/off with the flip of a switch, and it lasts through
any number of reboots (or power up/down cycles).