I’m about to change the rear band brake to a calliper set on my vintage dahon folder. Can anyone tell me if this would be a very stupid idea?

So the bike comes with band brakes with no available replacement parts and I can’t stop on them even after tuning cleaning and repacking.

There is a crossbar on the frame just above where the landing gear goes.

Would it be possible to drill into that bar and install brake callipers?

Any reason this might not work?

Why don’t bike makers ever put brakes down there but on the angled bit instead?

I can’t install it higher because the mudflap would be in the way.