I'd look into extending the brackets under the axle down to give you an attachment point that is straight out from the lift arm pivot points. Fabricate the bracket and bolt it to the axle.
Must be some other Mitsibushi owners that have accomplished fabricating check chains.
They may work in the criss-cross pattern on the inside between the lift arms, but from the pics, they would be in the way of the PTO shaft if a rotary cutter were used.