Hey sydost !
I have about 40 hours on floats and I would be really interested to fly seaplanes for a few years just a different experience. The companies you have checked i 've check them also already several times about their requirements. You may well land a job somewhere soon as a firefighter or seaplane pilot since you have already a fair amount of hours under your belt. Just keep trying and please let me know if you find a float company taking low hour pilots willing to pay for a type rating as well.
Cheers !