Alright! It looks like the MIL is going to get the green light to move into her house (and out of my basement) in the next couple of days! I finally got a couple of hours to play with things today. I got the frame cleaned a bit better, although it still needs another 4 hours of work or so.
I also got to try out the trickle filter and see if the bulkhead coming out of it could handle the flow that I want to put through it. Result: not even close. I placed my pump down into a 5 gallon bucket that was full and filled the trickle filter up to the point where the water was draining freely back into the bucket. The 5 gallons was gone in about 4 seconds. Just on a whim, I turned the garden hose on to full blast and stuck it down in the bucket to add to the flow - the bucket still drained in about 8 seconds. So...I can either redirect over half of the flow from the pump back into the bio-filter sump, which was planned for after the trickle-filter-turned-mechanical-filter, or I re-think how I want to do this.
The good news is that I'm no longer concerned that a 1200 gph pump will be sufficient for my needs here. Even better, once I get another 10 hours or so to work on this, the tank should be re-sealed and curing.