The only thing I can think of is something like this and maybe a heat pack or two, along with bundling up

https://www.walmart.com/ip/2-in-1-Double-Child-Bike-Trailer-Black-White/995990042?athcpid=995990042&athpgid=AthenaItempage&athcgid=null&athznid=si&athieid=v0&athstid=CS055&athguid=drveVD0zPXlKSp7_uUtEaVIPsF0Tcad64mr1&athancid=null&athposb=0&athena=true

You may want to give the Gardens a call at 633-8000 and ask how others with very young children have done there. They advertise the walk as about a mile, but that's a long ways when your child is cold. Good luck!