Point taken

the boot may be ok if you do not carry much in it, but the other good thing about carring it in the cabin is that if you hit from behind and it was in your boot well say good night. The best place is in the cabin with you either on the transmission tunnel which looks good or in front of one of the front seats preferably drivers side.
remember you might not need it for you but the guy behind, the choice is yours.

I would mount it passenger side, if it comes loose some how, it wont jam under the brake pedal !!!!