Then that's your problem, not the maintenance. With no indexes at all, no clustered index, the table is a heap. Firstly index rebuilds won't touch heaps, second deletes don't deallocate empty pages unless the delete runs with a table lock. Hence you have a table that's mostly full of empty space.

I've seen an empty table (0 rows) that when read processed 600MB of pages.

At minimum put a clustered index on that, and every other table in your DB. Consider other indexes too.