Hi, welcome to the archive.
Sorry to hear about your foot, those brown recluse's are nasty. Unfortunately I don't know of anyone who sells those kind of boots so you will most likely have to make them yourself. Also all of the shoes and boots from this time period didn't have heels, if that makes a difference. Although if you want, you can add a very low one and it will still looks fine.
A landsknecht light lancer would be a perfect fit for what you want to do and would be good for the early 16th century with a sallet. It was also one of Albrecht Durer's favorite subjects so I made a pinterest board with some of his images that depict light lancers.
https://www.pinterest.com/grimes0966/la ... t-lancers/
As you can see from the images that these boots were probably made from leather that were made very loose around the ankle and lower leg so you could get your foot into it. This loose part was then folded over and buckled or tied so it would be tight against the leg. The fold was started right at about where the pinky toe is and goes up to just below the knee. The boot tops could be either pulled up or left to drape around the ankle so I'm thinking that the leather (for the tops at least) was fairly thin. They probably let them down for comfort. The tops can reach over the knee which would have been good for wearing a 3/4's leg harness with. Also on the color images you can see that the interior of the boots were a different color than the outside. They were probably lined with some kind of cloth (linen?).
Converting these over to SCA use is going to be a bit of work, but you might be able to have some hidden armour under them? You could also add some armour toe caps, but I don't think that was done very much in period. Hope this helps.