Too much water for fruit trees?

We are looking at doing a modified hugelkultur bed about 125' long, with varying width (5 - 12'). The area is an existing slope that comes off of the road (there is a drainage ditch on the opposite side of the road which catchs most of the runoff from the road, although here in N. Idaho, we are are a veritable rainforest in the spring and fall (28" annual rainfall). The hugelkultur would be built up on the south side only, about 4' at the greatest depth, to bring the angle of the slope from approximately 45 degrees to near level on top for planting fruit trees. Basically we are just moving the existing slope out toward our garden to accommodate the planting of fruit trees on a more or less level plane and into what will become some excellent soil.
So the question is, does anyone have any long-term experience with growing fruit trees on a hugelkultur in a non-desert locale? I understand the fruit trees, especially prunus family (plums, cherries, etc.), do not tolerate wet feet, and this is the driest area on our property. Would we be shooting ourselves in the foot by creating an area that would retain too much moisture and in effect end up drowning the trees?
Also, what is the least angle of slope that a hugelkultur can successfully maintain (we want it as vertical as possible to allow a good sized path between the hugelkultur and a new hoophouse.
Cheers,
Ali

According to Sepp, steepness is important. He states that the most common mistake he sees people make is that the bed is not steep enough. It should be steep to prevent people from walking on it.

As far as water on the roots is concerned, personally, I don't think you will have a problem. The problem arises when the roots are actually in water, Damp soil is much different than standing water. The damp soil should help the trees during the hot, dry summer months.