Perhaps I've been working on old British motorcycles too much lately (big parallel twins shake pretty good) but I wonder how long a pipe nipple you could attach to the side of the block before vibration would eventually crack it. I've dealt with the heat issue by insulating the flexible line with pipe insulation and covering that with heavy duty aluminum foil. It doesn't look tidy but it saves the line from nearby exhaust heat. I've done the same thing with A/C hoses that run near the exhaust side of the engine and found the A/C works much better on hill climbs after insulating the hoses. So, I expect it works on the oil line. I haven't had to replace one in a long time.
I did use copper line for the bypass filter at one time but eventually it cracked despite the vibration coils I bent into it. It was mounted on the manifold. When it broke I couldn't find a 1/4 inch pipe plug in my tool box or lying around at the rest area but just then a trucker pulled up and asked if I needed anything. I told him I needed a pipe plug and by golly he had one. So I was back on the road in about 15 minutes. Whew!
Copper work-hardens over time from repeated hammering or vibration or bending. Then you have to anneal it with heat and a quench to soften it again. So be warned about using copper where it may be subject to vibration, such as long runs of it inside the oil pan in a critical application like an oil pump.
