Sweet bike!
Looks like you have 45cm chainstays (regular road bikes usually have 40cm chainstays). That extra 5cm helps the heel strike issue a lot.
You can't go wrong with Tubus if it's in the budget. There's not an awful lot wrong with aluminum though. You can get a plenty strong aluminum rack for any load that you would care to carry. For price/performance, I'd look at the Topeak Supertourist DX. Capacity of 55 lbs and it gets your load way back. The black finish will get dinged up, but that won't matter so much when you have bags on.