Another possible work around (haven't tried it myself yet) would be to use an ABY box to split your input into two chains. You should then be able to set up a parallel routing for both the A and B input signals, with your outboard gear placed inline with the B input. You could then set up a volume block, mixer block, or just two inverse CC's, so that you could bring in the signal of the dry aka A, or wet aka B, input, or a blend of both.
This would of course be before an amp block, but depending on the gear, that might not be a bad thing per say, and then you'd have the stereo FX loop free for post amp stuff (though could put it wherever of course) which I'd guess majority of outboard processors could utilize.