Ser William the boots you are referencing look very similiar to late 16th/17th century bucket top boots, but rolled up of course. I would say they would pass the 10 foot rule for that period, but I would be suspicious of them for earlier periods. As you say though, you are not in a reenactment group are doing this more for fun and general looks, so I think if you like them, they look periodish so go for it.
I had forgotten Viking Leather Crafts, though I have never dealt with them myself, I hear good things. Another place to look at is Reconstructing History. They have a limited selection of footwear, most for later periods, and clothing patterns for a wide variety of time periods. Prices are prettty decent, quality is good and they are very easy to deal with. I bought a pair of latchet shoes from them and am thinking of picking up another pair, open side instead of the closed side I got this time, and a pair of Kuhlmale Landsknecht shoes.