I have a Fender Mustang II amp, which I really like but it can only have a single-button foot switch, which I use for dirty/clean, so after some saving, I got a Boss Me-70 multi-FX which is also great, but the problem I'm having is that since the Mustang has no FX loop, I can't mix my amp's dirty tone with reverb or delay from the Me-70 and I can't really use phasers/flangers with the Mustang, because it's in front of the amp. So I was wondering if anyone knew how, or even if I could add an FX loop to the Mustang. I know it's possible with tube amps, but this is a solid-state modelling amp, so I was unsure.

Any help is great, thanks