Is it possible to finance a $23K trailer for 180 months?

$23k loan @8.49% for 12 years will be $255/mo.
$23k loan @8.49% for 15 years will be $226/mo.

If that $30/mo impacts your budget, I recommend not getting a TT or much less expensive one, maybe used. TTs depreciate about the same rate as vehicles. Maybe not quite as quickly as posted above, but it will be worth about half in 5 years (assuming well maintained) while the loan balance would be about 75% of the original loan. I recommend 5yr loan max for RVs.

What is your goal for the longer term?