Digging the tree up and raising it is the best course of action. If you are in a dry area with sandy soil you might get away with just digging a little well around the trunk but that's an inferior, lazy man's solution. (There are several problems with a tree planted too deep but one is wet soil around a trunk can rot it...)

The root flare should be just above the ground...you should just be able to see where the roots spread out from the trunk.

If they were in pots you might want to look for indications of encircling roots when you dig them up.

Root simulator probably isn't necessary.

see link on proper timing ....

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

the issue is.. in NM .... is this the proper planting time ... hopefully someone closer to your area will chime in ...

imo.. root stimulator is snake oil ..

also review at the link .... proper deep watering ..

presuming it is not a good time to lift the tree ... i would create a well ... perhaps using retaining wall block.. excavate down until you find the root flare .. then use the blocks to hold back the soil ... something like this .. note the soil stain on the trunk ....

http://www.nihb.com/block-tree-well/

ken

If concerned about root disturbance at the start of the hot season carefully dig the soil overburden away now, lift and replant after the leaves drop this fall instead.

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/Planting-fact-sheet.pdf

planted a 1.5” Sycamore & a 2.5” Purple Empress

==>>> its one thing dragging them across the lawn.. and dropping them in a hole ... what i would have an impossible time with .. is figuring out how to lift a couple hundred pound rootball ... from a hole in the ground.. without exploding a couple lumbar discs .. without machinery ... hence.. taking the easy way out.. as mentioned above ...

ken