I wouldn't describe any of that road as "tricky", and I don't recall anything steeper than the other highways in the area (such as 3). Direct from Kaleden to Keremeos on 3A is much quicker and easier than going all the way down 97 to Osoyoos then 3 to Keremeos, and that's what I would take.
97A? That's the opposite end and side of the Okanagan from this route... did you mean 97C, the connector between the Okanagan highway (97) and the Coquihalla near Merritt? The Coquihalla is great with a car, but the long grades can be a tedious grind in an RV, and 97C is at least as bad this way as the Coquihala.
Even though the 97+5 route requires going north to Peachland first, Google Maps
shows it as 30 km and one hour longer than the 97+3A+3 route, assuming that you are headed west of Hope. The time is based on a much higher travel speed on the Connector and the Coquihalla, which you are not likely to reach with a trailer. I would take the fast route in a car if I were in a hurry, and the south route through Keremeos with any vehicle to enjoy the drive... but I like Highway 3.