Apparently Iced Up

Even small amounts of frost can dramatically increase drag while reducing
lift. The comments about test pilot aside, there is no way that frost is
going to improve the performance of your airplane. At the very least you
will need more runway, have a reduced payload, climb more slowly, and have
your weight and balance thrown out of kilter. Your margin for error is
greatly reduced.

Now, add to that the factors of night, that ridge, possibly being tired at
the end of the day. I would hope that under the same circumstances I would
have the presence of mind to make the same decision you did.

Night with frost......no way. Safer to stay. You could wash it off with
prestone to clean the wing, but adding night into the equation is adding more
risk. If you did launch, be sure to think return options through the climb
out, that is if things weren't performing well, it would be time to return to
departure airport.
VL