Sharing my son with another family

Hi there , can anyone help me . I'm a solo dad returning to nz with my 2 1/2 year old developmentally diababled son.He's the sweetest thing but is probably only going to be with us for a limited time.At present he's at the 4mnth stage. Anyone want to share their life with an angel? I dont want to fall into the benificiary scene when I return. Was thinking about sharing him with another family somewhere around the Wgtn , Wairarapa or Manawatu regions. Ideally for 3 or 4 days weekly or possibly week on week off. Has anyone ever heard of this been done before? What other options might I have? Any thoughts much appreciated. regards Peter