Haven't done FP in a duckie, so not 100% sure...hopefully someone else with firsthand exp can chime in...but I'd guess for the most part at least, it'd be good to go still. Perhaps some "low" spots for a ducky, but I wouldn't think it'd be too bad at this level.
Maybe too mellow...and haven't looked at flows recently so maybe no good right now...but if there's water, you could do a stretch of the S Platte in town...starting at C-470, multiple take out options...the water is pretty clean on that end.
You noted pumphouse was a bit far...so this probably isn't a great suggestion either, but the Grizzly Creek to 2 Rivers on the Colorado is also a mellow option. Nice thing there is, if things go well enough and you have a tandem, you could then "guide" your mom or your wife one at a time down Shoshone for something more exciting. Pretty easy to find a ride, but can easily do the bike shuttle as well for both runs...