It's a cool idea and concept! Oregon Trail is a classic, but...it's also a frustrating classic, and one that is synonymous with cheap deaths and alot of trial and error to actually succeed. 
I never got to encounter any size mechanics at all, as I just kept dying. Whether from cold, starvation, or cold starvation. Everything functioned well enough gameplay wise, it was just not well explained enough so that I could survive. 
I think ditching the common elements of hunger, temperature, and so on for stuff that actually felt size-kink influenced would've been cooler. Maybe someone in the crew has blueberry affliction- which could boost the party energy while slowing them under the weight. Or a giantess roams, and you have to travel slowly to avoid detection. 
I want to believe there's that kinda creativity on display, but I just never got that far as the base difficulty hits so hard, so fast. For a properly big game with all the time and budget for it, this could be cool! For a game jam title, I'm left sadly deflated.