Three years is a long time to keep the glider idle in a trailer. You
should consider leasing it so that it gets aired out and exercised.

If you do decide to park it, don't put a plastic cover over the
trailer. I know someone who did that for 6 months and when the glider
came out of "storage" it was covered in mold. Now two years later you
can still see stains in the gel coat where the mold grew.