... and I don't know whether you saw my post 2 days ago about replacing the macerator pump, but near-freezing temps make a difficult job even more difficult (working with stiff sanitation hose). Heating the hose isn't an option if you don't plan to replace it, as heating would weaken it permanently. If you're more rational than I am you'll leave this job until warm weather returns.

As for containment -- good luck. I think your best bet is to sacrifice an old bath towel and/or disposable diaper and spread it out multi-layered beneath the joint. Sewage will start dribbling as soon as you start to work on separating the hose from the discharge fitting. That's going to involve a lot of twisting and levering and pulling (and maybe some cursing thrown in) to try to get it separated, and "quick hand work" isn't likely to be possible.

You might want to bring some Clorox Wipes or equivalent for the final clean-up, but don't use cleaners containing bleach on wood surfaces.