Help with router sled

Scratching my head here. I made this router sled out of 3/4 inch MDF to flatten this tabletop I'm building. I have this 2 inch flattening bit which I used to do two passes so far on the sled.

Here's my issue: the router is at its deepest plunge setting and the bit will not reach far enough down for the next pass. What's the solution?

I'm thinking a couple potential solutions: 1) make another sled out of angle iron so I eliminate the MDF thickness or 2) extend the router bit out a little more from the collett to make a deep enough cut. I don't know if this is safe or not though. Note: this is a 1/2 inch shank.

Is there something else I'm overlooking? I've watched about a million router sled videos on YouTube and they never address this issue. Seems like it would be a simple solution, but I'm drawing a blank here.