I work as a conservation ranger with the National Park Service, not state forestry, but some similarites do exist. One being that they both require a B.A. in wildlife management, ecology, or something in between. This differs depending on which exact field you work in, and a "foot in the door" can often mean a similar field of study but not exact one can get you a job. In the Govt. no certification test are needed if you have a degree, but I believe the state differs. I would suggest looking into an National Park Service or Forestry volunteer program, or seasonal work program combined with a current course load. If you have decent grades while studying look on USA jobs for seasonal work and be willing to relocate for positions.
I wouldn't trade a career with N.P.S for anything, but be aware the obstacles you face. 27 is certainly not old by any stretch, but many people your age are already working in the field with some time under their belts. I just turned 33 and have 8 years of service with an M.A. under my belt. So if this is what you want go for it with abandon now, do not wait any longer. Be aware inside and out of the govt. these positions are hard to come by, and state wages can be considerably lower then governmental. Competition is fierce because of the few jobs that are truly out there. The quickest way I see into this type of service, outside of Forestry school, is a combined study of Law enforcement and some type of outdoor studies. L.E. is always in high demand today, and it can lead you into a beautiful park with excellent hands on ranger duties.
Hope this helps.