Complicated SSRS layout - is that possible?
If you're using a single dataset which returns a single row, this should be pretty easy to achieve.

Not with subreports, but rather "sub tables". Create separate tables for certain areas, then drag and drop them in to appropriately sized cells within the main table.

Create a table, then another with the content you want to place in a certain position. Size the container cell accordingly (you can merge horizontal cells in the master to achieve this if necessary) or else things start to go a bit weird:



Then drag &amp; drop the sub-table in to place:



The tables have to have a dataset in common, which is fine in this context if I understand your description. And I think there are limits as to which area of a table you can place sub-tables, but other than that it can be a pretty powerful tool.

And I think your approach of ignoring headers and footers is right for this example. Just use detail rows for everything. Create as many as you need.

Hopefully I've given you enough to experiment with. I can expand on this at a later date if you need it.