Structs in CRUNCH

Dear CRUNCHers, I am trying to create a simple ring buffer and here are a few
issues I encountered.

The ring buffer is supposed to be very small and only contain bytes. It is
sufficient to have 4 fields: capacity, head, tail, and byte array.

So I thought this would work:

    (define-struct rbuf
        (cap char)
        (head char)
        (tail char)
        (buf bytevector))

Problem 1: That generates fields with 32 bits, not chars. I am programming a
microcontroller with CRUNCH and I want to have full control over such types.
The following worked, however:

    (define-struct rbuf
        (cap (typename uint8_t))
        (head (typename uint8_t))
        (tail (typename uint8_t))
        (buf bytevector))

Problem 2: Besides char not enforcing 8 bit fields, I also had the issue that
I forgot to include (crunch aggregate-types) and `chicken-crunch` gives no
reasonable error (no string) and simply returns an error code != 0.

Problem 3: Next, I want to define accessors. This is probably my fault, but the
following code

    (define-compound-accessors (struct rbuf)
        (mk-rbuf cap head tail buf)
        (cap rbuf-cap)
        (head rbuf-head rbuf-head!)
        (tail rbuf-tail rbuf-tail!)
        (buf rbuf-buf))

generates incorrect/unexpected modifier methods, eg, `rbuf-head!` becomes:

    void rbuf_X2dhead_X21(struct rbuf _s, uint8_t _x) { _s.head = _x; }

Only the copy of the struct in the scope of the function gets modified. I was
expecting to see this:

    void rbuf_X2dhead_X21(struct rbuf *_s, uint8_t _x) { _s->head = _x; }


Any feedback is appreciated. Thank you in advance!

Best,
- Diogo