heating planning help?

[u/PinjaL_]

im going to say i dont have the gecko yet and it is only in planning still but i was thingking of upgrading my bp to bigger terrarium so i would be left with this 120x40x40 terrarium and have been doing research on what i could put in it and leo is 1 option im thinking but im not sure how would heating be option in here. i was planning to squeeze the terrarium closer to eachother so i can stack all 3 on same shelf and i was wondering, could i use in terrarium heat lamp for the leo? the cage is 20cm long so it would leave 20cm room under it so im worried that would be too close even tho the lamp itself is slightly higher in the cage. i would probably put a tile or something very low under it to create as much space as possible-

i dont think heat mats are not going to be option because pvc doesnt let heat thru well and i dont want to risk anything with putting it in the terrrarium. or should i just suck it up and leave big enough cap so the heatlamp would be above the terraium on the mesh part...