I could put wheels on and lower the chassis to the ground, however this would limit the space underneath to work with the exhaust.
I opted for placing blocks under the chassis, raising it up by 100mm, but leaving a gap for the exhaust to pass through. I cut up some wood and held the blocks on the tressel using two pieces of 3/4" plywood and multiple screws. It is still solid to work on, only a little bit higher.
Perhaps if building another, the steel tressels could be designed to incorporate this gap to allow the exhausts to pass through.
I will dry fit the exhaust system to ensure it all works before sealing each joint and fitting the clamps.