It seems to me that it should be possible to use memcpy between multiple C variables to avoid straight type-punning, and then have the compiler reöptimize it into aliased memory or registers (assuming the source isn't volatile memory or something like that, in which case things get trickier anyway). This is roughly what I do in my C programs these days.
In some cases, declaring alignment may be hard to do portably; it's probably possible to use union tricks to force there to exist a dummy statement that implies certain alignment without breaking the aliasing rules, but I don't know for sure since I haven't run into such cases in practice yet.
As a nonrepresentative example, the simple function:
uint64_t foo(char x[8]) {
uint64_t y; memcpy(&y, &x[0], 8); return y;
}