I have seen vinal type bumper sticker material that would last a long time. Seem to me you could print on one and cut out the shape you need for various decals on the tractor/tiller. bw
Custom Decal in Taft TN 931-425-9139, did some deacals for me when I repainted my Yanmar Truckster. They turned out nice and were priced fairly. I took measurements and pictures before I stripped them off.