Hi RJ-n-Keli,
Welcome to the Heartland Owners Forum.
At the North American Rally last month, Heartland and the local Elkhart dealer worked with MorRyde on some specials including IS and disc brakes on a few new Landmark 365 units. I haven't heard that they're prepared to offer it as a factory option however.
You might call Heartland Customer Service at 877-262-8032 / 574-262-8030. Ask for Tom Montague, the Bighorn General Manager.