If you have a stand/the tools/the knowledge, it's probably a 15 minute job.
However, every time I think about (or actually build) a dual purpose bike, I just get frustrated by how it's not quite right for either of the tasks it's intended. I reckon the only way round it is to make something perfect (or as close as you can get it) for one use, but which can be quickly/cheaply adapted for another, which it may not be 100% at, but is acceptable. My Roadrat is this for commuting/touring, but they have pretty similar requirements compared to polo/mtb.
If you have a stand/the tools/the knowledge, it's probably a 15 minute job.
However, every time I think about (or actually build) a dual purpose bike, I just get frustrated by how it's not quite right for either of the tasks it's intended. I reckon the only way round it is to make something perfect (or as close as you can get it) for one use, but which can be quickly/cheaply adapted for another, which it may not be 100% at, but is acceptable. My Roadrat is this for commuting/touring, but they have pretty similar requirements compared to polo/mtb.