You can use most anything without issue, BUT........
The thing you have to keep in mind is you are trying to do the equivalent of field growing to thicken trunks. To get that result as quickly as actually sticking them in the field ground, the ecology needs to be the same as if it were going to be in the actual field, but with the addition that in your case, it also needs to be well draining.
A few things that make a huge difference in the field vs. in a bed in terms of ecology or to be more specific the micro-ecology.
1: Beneficial root fungi. This exists in nearly all top soil that is within a mile of any other tree. Endomycorrhizal fungi and Ectomycorrhizal fungi, as well as Trichoderma. They form a symbiotic relationship with the roots of nearly all plants and trees helping them to reach more water and nutrients and better absorb minerals. Thus greatly increasing a trees growth rate. Also they inoculate against many types of harmful fungi. You can find all kinds of this stuff for sale. I could write a book on the topic but nobody here wants to read all that.
2: Soil Organic Matter. This is the animal and plant residues at various stages of decomposition. The best "time release" fertilizer in the world, and also needed to keep your beneficial fungi alive. There are hundreds if not thousands of micro-organisms as a result of this in your soil, all of them are important to your trees growth and health. I could also write a book about this here, but I'll save everyone the 5 page reply.
3: Worms. There is likely no tree that you cant dig a hole near and not find worms. Not only do they help get more air into the soil, they leave behind castings from eating your organic matter which is another great natural fertilizer. Depending on how deep your raised bed is, the best worms you can find for this are called Red Wigglers. Just google it, they are not that expensive and work wonders. They are the best little root farmers you can hire, and they work for scraps. Literally.
All of the above builds a similar micro ecology to what a tree will have in the ground, the nice thing is once you get a good micro environment going it will live for hundreds of years as long as you supply the organic matter and don't kill off your fungi with fungicides or high doses of fertilizer. So.... Although the cost of starting out might be around $100 for a couple of raised beds, as long as you tend them you'll never spend that money again and you will have an amazing place to "field grow" your trees with great results and quickly.
Our 4'x12'x 2' deep beds consists of inorganic pro mix and compost (75% inorganic 25% compost) Then we mix in to that mix about 5% lava sand to balance PH, and increase drainage and 1 bag of perlite for drainage as well even though there is perlite in the pro mix. We use 2 bags of mycorrhizal fungi per bed, there a lots of brands but we found that rootgrow has the highest spore count per tsp so we use that, we also mix in 1, 1Oz. bottle of great white brand for the trychoderma it offers. Then we put in about 500 red wiggler worms to start the bed, they breed quickly so in no time you will have thousands in your soil mix.
We have seen equal, and sometimes better results in our beds as compared to the trees that we literally put in the field with a tile below them. In most cases for the shrubs the results are 25-30% better than in the field (shrubs being junipers in most peoples cases) Trees are just as hardy as the ones in the field, and depending on how the micro ecology is working we often find that after 2-3 years of being in the raised bed the trees out-perform the ones in the actual field.
If you have a season where you wont have trees in them, grow potatoes, it will help the micro-ecology thrive and be super ready for the next batch of trees.
Sorry for the short book reply, I was a horticulturist before a bonsai artist and for me the science of growing magnificent trees is just as much an art form as styling and wiring them.