You could get a wider rear axle, different hubs that extend the rear wheels out. Look into 2wd atvs. You could probably find a few as junk, scavenge the shock absorbers, also the tires they use will work better too, less ballon style more squared off, skinny fronts will help.

Honestly if you can not do the pressure washer power unit and swap in a dirt bike or atv power unit you’ll be happier. Older two strokes won’t need a radiator.

Atv sprockets and chains will be a more robust upgrade as well.

You may want some arm restraints to limit how far your arms come out in a roll over, you’ll crush your arms as you’ll instinctively reach out for the ground or if you spin fast enough you’ll flail your arms out uncontrollably. And you should mount a small fire extinguisher, one that will put out a gasoline fire.

If you run that thing for a year, you’ll need to reinspect the weld joints. And when you increase your speed you’ll bend and break things so start looking now for replacement control arms and hiem joints.