Use the wife's ladyshave trimmer for the main bush trim to about a No.2, then a good ol' trusty Mach 3 turbo with Gillette sensitive gel for sack, crack and lower shaft. Works for me.... and yes, SPs will appreciate the effort so long as you are nice and clean there too (not at all suggesting that you are not, mind you). No point being nicely groomed but smelly and smeggy down below.