Is this a legal bumper config?

[ksafin]

Had a quick question with our bumpers..

We're having a WCD this year and found that it was too low to the ground to mount bumpers. We could space up the bumper and attach it to the drivetrain frame but were wondering if the following was legal:

We have a mezzanine attached to the top of the drivetrain frame as a support structure to mount all of our stuff.. would it be legal to mount our bumpers to this mezzanine?

That is to say, is it OK to mount the bumpers to some upper support structure rather than the drivetrain frame? Is the "FRAME PERIMETER" the drivetrain perimeter or can it be the perimeter of the mezzanine? (which are the same)

Here's a picture to show what I mean.
You can see a side view of the WCD, with two channels at each end that are vertical and a horizontal bar (this is the mezzanine). The blue represents a bumper mounted to the mezzanine channel.