How to build up height of concrete wall to use as beam support for deck
Your final suggestion is probably the simplest, but you don't need to run anchor bolts all the way from the top of the sleeper beam. You also don't need a top plate. Just bold down the plate, then fasten the other two beam components to it.
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If you'd rater keep the space over the beam open for airflow or light or whatever, you can probably find an elevated post/beam support that will reach that far and not break the bank. Then you could put in a flush beam, like the one at the center of your current plan.

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You'd need to install supports at intervals that suit the beam size and load.