My most successful brew to date has been Northern Brewer's Scottish 80/- extract kit. It was a dead ringer for Belhaven, but lacked Belhaven's body and mouthfeel, maybe due to the fermentability of the extracts in use.
I'd like to do a mini-mash next time with the focus on adding body to the beer. The extract will provide much of the fermentables, so I don't care if this mini-mash is skewed very strongly toward dextrins. How do I adjust the mash temperature to lend body?