Vacants or acquired structures can be outstanding training opportunities as they stand but a few simple adds can help you get a few more repetitions. There are commercially available products like Force Plates or you can get creative with some standard construction materials and build your own. Here is one of the Do It Yourself options I found that works pretty well.
2- Simpson Strong-Tie Z-Max 16 in. Heavy Duty Strap bent to shape in a bench vise
24 – 1 3/8″ deck screws and as much 3/4″ plywood or wood shelving found in the building ripped down to 2″strips as you care to use