The twin cooler setup really is over kill, so you will be fine I reckon.
I run a setup similar to the S2 twin cooler setup on my S1 and the biggest problem I had was getting the oil warm enough.
Sustained Motorway trips (unless you are cruising at 150mph) are easy as you are doing a relatively high speed, at relatively low revs. i.e. cruising in 6th gear.