Answer: I would not recommend planting even the more sun tolerant hostas in full sun all day or in direct afternoon sun. The golden hostas are the more sun tolerant and will tolerate direct morning sun, even all morning quite well, as long as the soil is evenly moist. The blue hostas are the least sun tolerant and in my experience really must have shade. Most hostas though will do fine in a few hours of direct morning sun or very bright dappled light all day.
The caution I would have about planting on a hill is that the soil may be quite dry at the top and mid slope and then naturally a bit damper at the base. The hostas would probably do better where the soil is moister.
If you have, for example, a slope with hot afternoon sun your hostas will not do well there. You might try a sun loving plant that tolerates dry soil instead. Your local professional nursery staff should be able to help you select plants that would thrive in the conditions you have.
I hope this helps.
Q&A Library Searching Tips