As with most operations you will start life in the right seat. The actual requirements aren't onerous - I think the USFS requires 800 hours PIC as well as the usual certificates and ratings for a copilot in a tanker on contract.
Keep in mind there really aren't that many planes flying. About eight or nine companies each flying a few tankers. Probably only 25 planes in service on USFS or DOI contracts in any given year, so 25 theoretical FO positions in a season (unless they have relief crews, not sure.) There are state contracts too, in Oregon, California, Alaska, Arizona, probably others...
Expect to occupy the right seat for three to ten years.
Lifestyle is: no personal life for summer traveling all over on short notice making mid-thirties over four or five months work.