hid fog light ballast mounting

i have searched with little results
where is a good place to mount hid ballasts for the fog lights?

I'm looking to do a clean install and hide as much as possible (within reason)

i have older large ballasts so i cants use adhesive

I have mounting brackets so i need a bolt or drill access

I will not stack them on my other ones (saw that some people do)

I'm running out of room and ideas ... please help

pics are appreciated

here is my current install locations
drivers side (+relay):



passenger side :


Relay harness: