Lake Haven is open year round on the south side of Indy. they have a website,
http://www.lakehavenretreat.com/About_Us.phpMy personal favorite for ease of finding, etc., just off I-70 to the east is the Indy KOA. I believe they are open all year. As KOA's go, they are a bit pricey, but it would be off season for them. Easy access from the interstate and you can't find better owner/operators. Very friendly and accommodating. We stayed for 3 months starting in March one year when I had extensive back surgery. The address is actually Greenfield, but it's very close.
https://www.indianapoliskoa.com/Dale