Alan -
The reason this is complicated is that you're suffering from stereo/mono schizophrenia here. The Furman board is designed to take a mono or stereo input, route it to the stompboxes, and maintain independent stereo channels back to your (two) amps. This is really important if you've got a stereo chorusing device and want to maximize the effect at the amps.
But from the general info you have here, you're mostly running a mono signal path. So, life will be easier if you ignore the upper row of patch points on the Furman pedalboard.
So, I'd actually do something a little different. I think you want to go from bass->DS-5R, then take the DS-5R BASS/MONO OUT and put it into the IN of the tuner. You definitely want the tuner ahead of any effects (obviously, tuning will be messed up if you had a chorus!), and putting it here lets you use the mute footswitch for tuning as well.
From the OUT of the tuner, go to the F-1X front panel INPUT. From the F-1X EFFECTS LOOP SEND, I'd go to the chain of pedals in your pedalboard. The end of this chain connects to the LEFT IN FROM PEDALS input on the SPB-8C.
Connect the LEFT OUT TO AMP output to the SF-2's CHANNEL A INPUT on the back panel. I think you want to set the SF-2 to mono too. It's not completely clear how this guy works from the website description, but it looks like connecting on the A channel will give you the ability to blend the original signal with two filtered outputs.
Take the CHANNEL A OUTPUT from the SF-2 to the EFFECTS LOOP RETURN on the F-1X.
And finally, take the LOW-PASS and HIGH-BASS outputs of the F-1X to the appropriate amp inputs.
I think this would work pretty well. The main option that you have is whether the SF-2 is before or after the pedal board. Unless you'd like to apply sound shaping before an effect, you'll probably find that after will work better just in terms of keeping your routing simpler.
If you decide to go (even more) gear crazy, then of course you'd want to come out of the DS-5R in stereo to both of your F-1Xs, which would feed both channels of your pedal board, then come back and feed both the stereo bi-amps and speaker stacks...
Hope this helps,
David Fung