Configuration and Timing values to acheive Maximum range in a TWR system

I have created a TWR system that seems to be working.

static dwt_config_t config = {
    5,                /* Channel number. */
    DWT_PLEN_128,     /* Preamble length. Used in TX only. */
    DWT_PAC8,         /* Preamble acquisition chunk size. Used in RX only. */
    9,                /* TX preamble code. Used in TX only. */
    9,                /* RX preamble code. Used in RX only. */
    1,                /* 0 to use standard 8 symbol SFD, 1 to use non-standard 8 symbol, 2 for non-standard 16 symbol SFD and 3 for 4z 8 symbol SDF type */
    DWT_BR_6M8,       /* Data rate. */
    DWT_PHRMODE_STD,  /* PHY header mode. */
    DWT_PHRRATE_STD,  /* PHY header rate. */
    (129 + 8 - 8),    /* SFD timeout (preamble length + 1 + SFD length - PAC size). Used in RX only. */
    DWT_STS_MODE_OFF, /* STS disabled */
    DWT_STS_LEN_64,   /* STS length see allowed values in Enum dwt_sts_lengths_e */
    DWT_PDOA_M0       /* PDOA mode off */
};

My configuration is as above.

I am using the DWM3001C and am getting terrible obstruction when close to a persons body. Is there any way that this can be improved, rather than asking my users to hold the thing on a broomstick above their head?

Also it would be great if someone could help with the timing values to acheive the maximum possible range as well as how to change the configuration for both the RX and TX in a TWR system.