Platform undercoating - black tar vs. fiberglass

[DoctahDeane]

I have read a lot on this topic. I know that many go with the tar stuff but it also seemed that fiberglass could offer some benefits. I talked to reps at System Three who make a popular boat epoxy. Sounds like nasty stuff but also, the rep mentioned reapplication every 3-4 years ( I suppose that is for a boat?). Anyway, it seems that reapplying glass underneath a "done" trailer could be quite a hassle and although messy, the tar stuff could be easier to reapply (if anyone even does?).

Any thoughts on this? I am ready to attach the platform and move on top the profile and sides. Thanks!