A Surrogate template, passing in parameters? (advice/help)

[ChickenMobile]

I am trying to create a DPL query which generates a table for a series of items.

{{#dpl:
| category        = Bard Spells
| include         = {SpellTemplate¦SpellRowTemplate}
| resultsheader   = {¦ class="wikitable sortable" ¶!colspan=16 class="unsortable" ¦Header 
| listseparators  = ,
| resultsfooter   = ¶¦}
}}

The problem I am facing: is that SpellTemplate is generic (including all class spells) and I need to know what class I am querying to generate class-specific data within the surrogate template SpellRowTemplate.
Usually to insert parameters to a template, it would look something like: {SpellRowTemplate|class=bard} but I don't see a way to do this within examples included in the documentation. e.g. | include = {SpellTemplate¦SpellRowTemplate¦class=bard} (will not work).

I tried defining variables outside the DPL query - e.g. {{#vardefine:class|bard}} and accessing it within the surrogate by {{#var:class}} but they were always blank/null (as if never set).

Is there be any viable way to do this?
Any alternate suggestions/help welcome.

Thanks,
Mel