1400ft+ of climbing per lap. I’d say that’s anything but flat myself!
Anyway… Weight and mud clearance are usually more important than suspension. If it rains at all, fit the narrowest tyres you can lay your hands on. If it stays dry, count yourself very lucky, run the fastest tyres you can lay your hands on to minimise drag. I’d still not want to lug any extra weight up the hills at all though. Plenty of quick guys will be running full sus bikes, but they’ll be 100mm travel affairs and often made of carbon, not 160mm with slack angles and dual ply tyres.
Remember, even though you’re not competing, you will get competitive with yourself and others. A big heavy bike will be demoralising and will reduce the fun factor IMO.