Hi Jordan - I picked up a 2005 3.0d sport 4months ago - 2 owner with 110k miles for under €5k - I'm doing 450miles a week in it since I got it and touch wood it's been 100% fine.
I don't think mine had ever been worked hard but i know it had a new turbo 3yrs ago - gearbox is a concern in them but mine seems fine and I don't hammer it around too much - I'm seeing 30mpg on my 80mile commute which has some stop start sections (Limerick-cork road).
I'm enjoying it, drives well, had a couple of e39s before and it feels just like them. Towing a ton shouldn't be an issue. They're heavy on tyres (around 150ea front 180ea on rear) and suspension components and parts are pricey for good quality items.