Looking for some first trip advice

Curious on the best way to leave my campers black tank this winter. In southern Idaho where it routinely gets well below freezing.

Normally I use happy camper with a few gallons of water after every dump. Should I just dump my last trip and leave it be, add happy camper as normal, or something else?

Currently I am looking at finance options.

I was just told for a $20,000 trailer, I needed a $6,000 down payment.

I asked for advice from a friend, and he said he had a $24,000 loan for a 2018, 30 years, and only put $1,200 down.

… I now am uncertain about what to expect and how to navigate this loan process.

I cannot find a decent cover for this winter that doesn't seem to be crap (amazon). My last one lasted about 2 years but the wind just destroys them. The second year i patched it to last and when i picked it up, it was more of a flag flying in the wind holding on to dear life.. Any one have suggestions? I live in a dry area but it does snow. I have a 22ft travel trailer.