A month is not a "ridiculously long time" for a snake. Snakes conserve energy & fluids in nature...they're designed to waste nothing & survive fasting, so unless your snake shows an obviously swollen area above
the cloaca, I would not advise soaking her. Not that it will harm anything, assuming you stay right there & make sure the water is not too deep (less than the snake's height, so it doesn't have to swim) & is of the
right temperature (measure it...most ppl get the water too warm for snakes, because it doesn't feel warm to us unless it's over our body temperature of roughly 98.6*, which will be TOO HOT for a snake). The only
'harm' from soaking a snake is the stress it usually causes them. Stress is usually best avoided for snakes like BPs because they are easily stressed into not eating.

A snake that is showing "sausage butt" (noticeably swollen above cloaca) may defecate easier if actually allowed to swim in several inches of water (in bathtub) but you must be right their supporting their body so
they can "swim in place" until they get relief; if needed, this is an effective way to help a snake expel waste, but most do not need the help. Be prepared for a nasty bathtub to clean too, if you do this.

The "foul smell" might have been from the urates passed, but many snakes will also pass gas from time to time...fyi. Sometimes the "music" will tip you off, lol.

Bottom line: not unusual at all for a snake to eat a number of meals without defecating. Very normal. Your BP is eating...be happy!