A hacksaw is unlikely to work as the plates are too hard and it is not that easy to hold it still or in a position to get a decent cut stroke.
You can get a 110mm angle grinder for about £25
https://www.ebay.co.uk/itm/Corded-El.../274093166225?
or Screwfix also about £25
and either just grind the rivet heads off or get some 1mm (£6 for 5) cutting discs and cut straight through the plates.
If you are worried about petrol fumes just ventilate the space for a decent period of time until the smell is not really noticeable,