Using gains subject to capital gains tax to pay down debt on real estate in an opportunity zone

So I’m just learning about opportunity zones. Please keep that in mind as you read this because it likely contains incorrect assumptions.

The scenario – I have an investment I made, that appreciated rapidly over the last year and now I’m subject to a massive amount of taxes if I realize this gain.

My solution – I’d like to take these gains and put them into an opportunity zone in order to take advantage of the tax deferment benefits the federal government is offering.

The problem I’m trying to understand – If I have existing rental property real estate, under a loan, in an opportunity zone, can I use these funds to pay down that debt or does it have to be new investments? If I can’t use it, could I possibly form a company specifically for this opportunity zone investment and sell my rental properties to that company so that on the books it appears that it’s a new investment?

Edit
The investments subject to capital gains tax are a mix of long term and short term holdings from rent, stock sales, crypto currencies, and a sale of a rental property.