Shimano make a great pair of Hiking SPD boots, the MT91. Grippy Vibram sole and all. Last tour I used a pair of 510 Cyclone boots, they didn't have enough tread for slippery stuff. I climbed a couple of volcanoes in them on that trip including one climb of 6000 vertical feet in a day. I can't see the problem in hiking in SPD shoes designed for hiking or walking. Good walking boots have the same attributes as good bike boots, a stiff sole with a strong rigid shank. Have a pair of flip flops for the camp and some Sealskinz socks for when the boots are wet after riding and you want to wear them around, like going out in the evening.