At 23, Sydney man Lucas Fowler was travelling the world with the woman he loved and "milking every last drop of fun out of life".

His father, NSW Police Chief Inspector Stephen Fowler, on Friday told hundreds of mourners at Turramurra Uniting Church on the city's north shore, his son's lifestyle was one that many "envied".

Australian Lucas Fowler and his American girlfriend Chynna Deese were found shot dead along the Alaska Highway near Liard Hot Springs in northern Canada on Monday, July 15. Credit:AP

"He didn't just dream of travelling, he worked and saved and made it happen," Chief Inspector Fowler said.

Mr Fowler, an apprentice motor mechanic, and his US girlfriend Chynna Deese, 24, were found dead on the side of the remote Alaska Highway in Canada's rugged northern British Colombia last month after their Chevrolet van broke down.