Is there a way to configure 0.8 to not increase the block size over the limit?
The default settings won't produce problematic bugs. Probably.
Because the bug (can't handle blocks over a certain size limit) isn't in 0.8 its in 0.7, and the bug cannot be resolved unless the entire network abandons 0.7 and earlier.
The bug is that in all versions of bitcoin prior to 0.8 the maximum number of transactions that can fit in a block is not universally definable, because the limit varies based on the exact hardware and software configuration a particular node happens to be running.
It's possible for 0.7 nodes to produce valid blocks that other 0.7 nodes can't process.