No substrate depth in not an issue, substrate lenght is.
This thing about digging has without question gone stupid. All people think about is digging. I have an idea, why not think about why they are digging.
Birds flew. But would you call keeping a bird in tiny cage standing on its perch flapping its wings, FLYING. No, its flapping its wings. Which a bird does when flying, but its still not flying, its just flapping its wings.
Which leads to this, monitors dig for reasons, they dig to make a burrow. A burrow must be longer then the monitor, or its not a burrow, its a divit. They dig a burrow to make a home, something that allows depth and safty and comfort(right conditions)
Lets put on the thinking cap, a six foot trough for an ackie(18 avg. lenght) it can burrow four times its lenght, three longwise and one shortwise. It can also turn again and make a burrow six times its lenght. A rudi is much much longer and much much wider. So to have that for an average rudi(four foot) then you need a 16 foot long cage. But in reality that is still much smaller as the mass of the rudi is far more then four times the ackie.
So yea, that cage would be great for a small lizard like an ackie or storrs, or tristis or kimberly.
Then you stuff things in there for your enjoyment, a budda. That takes away from what the monitor can use.
Now please consider, I hit you with this a little harder then I do most, the reason is, YOU SHOWED THE ABILITY to actually do something about it.
About the crickets. The advantage of crickets is, you throw in handfulls and monitors can eat them at their leisure. That is not done with other prey items. People foolishly thing reptiles are people or dogs that are fed a few meals a day, only with monitors people feed heavy meals one a day or less, sometimes muchless. The reality is, they eat all the time, lite feedings, many times a day and heavy feedings several times a week.
You feed your bird daily, in fact, you leave a bowl of food in with it. An active monitors is near bird like in metobolism.
Which leads to this. The one reason folks are more successful with ackies is, they are little and its easy to feed them enough to allow success. With larger monitors, that is not done. Think about this, how would an ackie progress feeding on three crickets a day. By size comparision that would be like feeding three adult mice to a rudi a day.
I can go on and on, but you should get the idea, To keep a rudi at the same level most people keep ackies, you need a room size enclosure and hot areas as large as your cage is now.
Other then your cage allowing crickets a free pass to your house, you did a great job, just not for a living monitor. Oh one more thing, how will those logs stand up to years of hot and moist?? don't logs warp in those conditions. Cheers and happy cage building(where the real fun is)