If you can remove the screws, I would consider using the Bosch Fine Cut saw. It is intended to cut door trim flush with new flooring. It has a very thin blade with the teeth slightly offset so you can lay the blade directly on the floor without damage to the floor, while cutting the trim. The blade can be reversed for right to left or left to right cuts. It does a great job. I actually used mine to trim the hatch width on my TD instead of a router with a flush trim bit. I just laid the blade flat against the outside wall of the TD and trimmed the overhang off of the hatch.
If the screws could be removed blades would last longer as they are not cheap ($15.00). You could lay the saw flat on the floor on the inside of the tear and use the floor to guide the blade for clean flush cut with a very thin kerf. You might have to wedge the kerf occasionally to keep the weight of the wall form bogging down the small 3.5 amp motor but it actually cuts very well. There is little or no vibration so it is easy to control and the thin blade results in very little sawdust.
You can find the Bosch Fine Cut saw at Lowes for around $100. with a blade or two.
