Bearded Dragon "Glass" Surfing?

Gods, I haven't been on here for many years. Anyway, recently picked up a bearded dragon who's constantly "glass" surfing. It's in apostrophes because the tank isn't technically made of glass.

It is a 100cm X 60cm x 30 cm opaque plastic tub. Temperatures are about 86F in the cool end and about 95 F at the hot end. One possible issue is the humidity which can't quite be helped because I live in a tropical country, it usually runs between 30 to 50% RH with the help of heat bulbs; otherwise it would hang around 70%. Other things that I can add is that he rarely uses his hidebox and he is a male based on observations for double hemipenis bulges and according to the previous owner. Anyone can identify a possible cause to his "glass" surfing?

Also, he is constantly smearing his waste matter all around as a result of these habits. Would sand or any other substrate make the task of cleaning significantly easier? I end up having to brush waste from his tail rather often.

It's newspaper he's on. He tends to push it all aside when he's attempting to scale the walls and ends up defecating on the bare cage surface.

I haven't raised the temperature mainly because of my fears that the ambient temperature would become insanely warm, and the fact that he does generate well formed faecal pellets make me guess that digestion hasn't been an issue.

Behaviour wise, what I've observed is some pattern where he will wake up, take it calmly, basking lights are on and you give it an hour. Chaos. I have a video which I can try to upload.

I definitely like the look of slate tile but I'm just slightly concerned about hygiene. Don't mind me but what do you do with that wet cloth after giving it a wipe? Does the tile not also remain generally dirty?

The air temperature here is at 30 degrees in the day on average, it can rise to about 34 degrees on really hot days, there really isn't much I can employ as a cooling technique to be honest. I try to keep the room cool with a circulating fan, and I also keep the aircon at 24 degrees celsius through the night and into the early morning. Subsequently, I usually leave the windows of the room closed until the temperatures are equalised. It might be worthy to note that he is captive bred in this environment. I'll get the videos up of his behaviour as soon as I make a relevant youtube account.

And I really went for the tub mainly because I thought it would leave him less stressed due to glass surfing. Okay here's the plan. Because the tank is situated next to a wall, I am thinking of removing the mesh which is currently supporting the UV and heating bulbs. Instead I will suspend both bulbs from the hooks placed on the wall. In that event, some driftwood can be placed in the centre of the cage, rising out of it, which will help to give him perspective. What say you guys?

I am not considering an alternative set up because frankly a tank would cost in the region of 200 dollars local currency and I would find myself struggling with the height. However, should it prove truly necessary, then I will go ahead.