Lots of people recommending what they'd buy, not a lot sharing what they currently ride.
I've had a lot of fun using my soma double cross disc for these types of rides. 700x40 tires and wide-rim road wheelset. Position set up for comfortable road riding but it works great for single track too.
It's almost as fast as a my regular road bike on the road. It's not nearly as fast as my mountain bikes on the trail but is about as fun. Similar to riding rigid v. suspension, you can go fast but it's more about finding a smooth line. My usual trails are rocky, rooty singletrack with a lot of elevation change so it's a good litmus test - I've tried other carbon/aluminum bikes and they do not handle the rough stuff nearly as well as the steel frame/fork.
I've also had it set-up with a front rack and frame bag and can get about 15 pounds of luggage before the ride becomes too much work to keep tracking down the road. It handles gravel ok but I'd probably go full bikepack if I were doing a lot of singletrack with luggage - loaded it tends to resist lean/turning and then dive into the corner - disconcerting on singletrack.
It's not $5000, although honestly I'm not the sure there's a multi-surface bike with features available to justify that purchase price. Bikes in that price range are generally just trying to convert the road racer market over to dirt using marketing and R&D concepts that capture their attention but are usually specious for unpaved riding.
No one really wants to hear "buy a cheaper steel cross bike" so I'll recommend the Diamondback Haanjo EXP or the Raleigh Stuntman because they're really well engineered bikes and both offered for sale at a great discount.