I have a Yanmar YM1700. I talked to a friend that works at a local steel fabricator about cutting out the "suitcase" weights from 1" to 1 1/2" plate on his N/C controlled plasma torch. The cost turned out to be more than they were really worth.
At his suggestion I built a box and bracket out of 1/4" plate and bolted it to the front bumper. After I built the weight box he gave me all the punch slugs I needed. This probably added 25 lbs for the box and bracket and another 75 or 80 lbs of slugs, I didn't fill the box full, so, I could put more weight in it if needed. Total cost of this project was probably $10 or less in materials and my time.