It doesn't seem unreasonable to me to simply use the ammonium salt in the formation of the amide as long as you have a whole slew of alternative base. for instance, if you run your condensation in something like 1:1 pyridine:solvent or even with pyridine as the solvent alone, you will get an equilibrium from the ammonium salt to the pyridinium and the free amine which can then go on to do further chemistry. this would be especially useful if the amide formation is acid catalyzed because you would be using the proton you already have. even if your salt isn't all that soluble in a particular solvent, any amount that does enter the solution will quickly form the free amine (again, a function of an equilibrium between the large amounts of pyridine and small amounts of amine) thus pulling more ammonium into solution since it is consistently being pulled from equilibrium by deprotonation. hope this helps