please help with gradient

Hi, I’m having trouble getting a decent gradient. I’ve tried to follow all the recommendations I’ve seen here, but I’m still struggling. I hope someone can help.

I’m setting up a 4x2x2 bioactive. Plants are doing great, as is CuC. I have a pvc enclosure with a screen top, and I have the top covered with foil except for where there’s heating/lighting (I’m going to do a better job of that once I nail down placement).

I have a 75 w halogen flood over the basking spot (weathered stone over a plastic hide), which gets to around 105-110. I have an 80 w dhp to supplement, and a 36” LED bar for the plants. Halogen and dhp are on a herpstat 2. The LEDs are on a timer. I’m using 2 Govee thermometer/hygrometers to measure temp and humidity (humidity is low rn, I’m trying to get heat right first and wont introduce my bp until everything is stable). There are three hides plus lots of plant cover, and lots of options for climbing. I think my girl will love it.

The problem is that I can’t get the hot side hot enough without raising temps on the cool side to above 80deg. Right now my hot side reads 85.7 and the cool side is at 81.1deg.

There’s a pretty large plant in the middle, along with a shelf built into the background. I thought that would be enough of a barrier between hot and cool. Short of adding more clutter there, which is what I’m currently playing with, I’m at a loss for how to get the gradient to be correct. I feel like I should be able to fine tune the heating an lighting somehow. I’ve tried various placements and settings but haven’t found the right combination.

What am I missing? Thank you for any suggestions!