My only suggestion is that you can have warmer spots within a greenhouse if you "add layers" above and below. Maybe not the entire, u nheated greenhouse is warm enough for something, but you could maker a few spots extra-warm.
You can easily drape a floating row cover over some plants to give them a few more degrees of warmth.
You can set up some wire hoops or use stakes for "tent-poles" under heavy plastic film, to put a very low "mini-hoop-tunnel" over a row of plants inside the greenhouse.
You COULD go even further like one author did in Maine, and put a tallER hoop tunnel over the LOW hoop tunnel.
None of those will help much if the table the plants are on provides little insulation, or even worse, allows a draft to rise and flow around the plants, drawing heat away. But some solid shelving under the plants will cut drafts and insulate against heat conduction downwards. (The row cover and hoop film reduces heat loss upwards.)
If you take the trouble to look for "sheet rock" = "Gypsum Board" = drywall, and put a sheet of that under some plants (with plastic to keep water off the drywall), you will have excellent heat insulation under the plants. That will greatly boost the effectiveness of row covers or plastic film in a greenhouse.
You might not get a whole ten degrees F improvement with each layer, but you WILL keep that one spot warmer than the rest of the greenhouse, longer into each night.
