Been watching similar stuff over here in the UK so I can't speak to your specific river, but the pattern you're describing - large bipedal stride, irregular spacing, deep toe impressions - sounds very familiar from the Bigfoot evidence database I've been cross-referencing for the past few years.
Winter prints are honestly the most valuable ones because the ground holds detail better and you get less contamination from vegetation. If anyones got proper casts made I'd love to see the dermal ridge detail, thats where most researchers fall flat because they rush the casting process.
What's the stride length measuring out at? That's the first thing I'd want to nail down before getting too excited, because deer slots in snow can do some genuinely bizarre things when they melt and refreeze overnight.