[Scott Squires]

Have you tried a cable from the Tascam with the boom input into your camera? (instead of using the Tascam built in mics) There are special cables to make sure the levels are correct.
https://www.bhphotovideo.com/c/product/746643-REG/Sescom_LN2MIC_TASDR100_LN2MIC_TASDR100_Line_Out_to.html

One thing suggested to me by an audio guy is to a wireless plug for your boom mic.
https://www.bhphotovideo.com/c/product/618735-REG/Sennheiser_EW_100_ENG_G3_A_Evolution_G3_100_Series.html

or get the plug and recieiver separately
https://www.bhphotovideo.com/c/product/618848-REG/Sennheiser_SKP_100_G3_A_SKP_100_G3_Plug_on.html

https://www.bhphotovideo.com/c/product/618925-REG/Sennheiser_EK_300_IEM_G3_A_EK_300_IEM_G3.html
but the combo gives you 2 transmitters and a lav mic in addition to a receiver and the xlr transmitter.

The advantage is it provides the quality of the boom mic without the issue of cable noise on the boom pole or cable impairing movement. You’d probably want/need to go through Tascam or other box before going into camera but I’m not sure.