It’s not legal to use a 3500 kg rated tow vehicle to tow 4500 kg, and your insurance wouldn’t cover you in the event of a crash. Step up to the bigger vehicle, or maybe look at something like a RAMpickup.
Disclaimer: You acknowledge and agree that all answers are provided as a general guide only and should not be relied upon as bespoke advice. CarsGuide is not liable for the accuracy of any information provided in the answers.