Heating pad or heating cable on the sides of the tank is the best way according to me, if you reach required temps on the substrate.
Then you add a Retiglo 2.0 UVB 13W for example as light source.

Yes, Basking spot is more agressive , but in africa, sun can be agressive too

If you use a basking spot, it's a spot without UVB's that you have to use (Only UVA's).
Try to not go over 60W and keep your substrate moist + air humidity at level of 70%-80%.
Put some hidding parts in the tank also (Wood barks, plants...etc...)
Those frogs need to hide, they feel more safe.

Advantage of basking spot is that it creates a hot spot.