applying for visa 820

Hi there, im a Scottish citizen and will be applying for the partner visa 820 as my NZ partner is now classed as a protected SCV holder. We bought and have been living in a motorhome with our baby daughter for 2 months and dont have much evidence regarding utility bills. We do have the receipt and insurance with joint names but that's about it. Can anyone advise any other documents we could use? My partner has just started a new job after travelling for 2 months.

We have just returned back to Oz after living in Scotland for 3 years.
We have a correspondence address.

I would be grateful for any help.