Heartland is installing, as an option on Landmark (not sure if available on Bighorn), a 4 leg version of the Trailair Level-up...we have the original 6 leg version (2 landing gear and 4 legs surrounding axles)that was installed after-market. Our version, as we needed to have the front landing gear replaced (unit came with electric), cost around $3,500, which also includes a remote control.
Not sure if Heartland will install the 4 leg version during construction...can't hurt to ask. If you go aftermarket to Trailair, I'm pretty sure they will recommend the 6 leg...but again, you can ask if they will install the less expensive 4 leg version. Good Luck!
By the way...we LOVE the Level-UP!!
Sorry...just noticed you already bought your Bighorn...call Kara at Trailair (800) 998-4238