Protecting Citrus Trees with temporary plastic greenhouse - Need more insulation?

Pics of setup currently - https://imgur.com/a/9p5tBfc

I live in Houston TX and in the back yard I have a Meyer Lemon, a Key Lime and an Orange Tree.

In 2021 we lost all of our citrus, so we vowed to never let that happen again

The first few years moving blankets over them worked fine, with a tarp over the very top to help with rain. However as the trees get larger and larger its a lot of work and the clothes are too small. We also put 100w light bulbs under each one

So this year I got some temporary plastic greenhouses, and along with the 100w bulbs I found some 200w space heaters. Everything is automated based on outside temp. Below 34 the light bulbs come on, and below 30 the heaters do

Do you think I need to add sheets to the inside, or will the plastic be enough? I could add sheets to the inside I think no problem