Hi Glen,
as usual, i think there is no "best" way for a trackbed.
It depends on what u want to have.
With track power, i would always choose a concrete, stoneplate or glued balast track for keeping it free from weed and things.
Me, i us RC control and accu power, so dirty tracks are not my problem, or cleaning them (for what the glued balast ist best).
I have layed my track on a bed with 2-3 layers:
first i digged out the line about 8-10 inches wide and 1-2 inches deep.
In this i layed a foil (old plastic bag is enough) to hold back weed and grass growing.
That i ballasted with about one inch stones (the "edgy" ones, not round). Do this untill u have it even to the ground besides.
With the same stones i made a kind of fence, a little wall to the sides.
That was all stampped dowm by walking on it, giving the middel a level and give the sidewalls densitiy and form (soft house shoes are great for that, but wifes have normally something to say against that...).
now u fill a little layer of gravel in and make a "planum", giving it density as told.
Then comes the track. Level it. I filled a fairly big wall of gravel over the track. make it even with the track with a small shovel or a little board.
I now have "stomped" the gravel with a 10x10mm wooden bar beneath the ties. U feel, when it gets hard. Then its really under the ties.
With a very hard scrubber i give the whole thing a form and clean it a bit to get the driveway free of gravel (be carefull to get the little gravels that are pinned to the tie-screws).
"scrubbering" the gravel in the surface condenses one more time and u can give the outside a form.
Advantages:
easy for layout-changes
no concrete-blocks that makes our garden a desert (if u overdo it with the concrete...saw such layouts).
track can move with temperature
easy to build.
easy to repair.
Disadvantages:
no hard fitting: dogs or kids running over the track will tear it out.
no 100% weed controll. Worms and little floatings will carry soil to the gravel. That is bed-stabilizing, but dirty and tends to be setteled with weed (therefore the foil: u can pull out small plants very easily).
Greetings
Frank