i'm in the middle of all this right now. i have an icom 706-mkiig, an
old laptop, etc, and have been prototyping a basic setup to do all of
this, including airmail. i haven't gotten very far because i passed
the written tests for "extra" but haven't taken the morse test yet, so
i haven't been on HF. through a really dumb mistake i also hooked one
of my deep cycle's up backwards and burned a diode in the icom (and
another radio) and had to send it off to have the diode replaced, so i
have been waiting a week or two on that and haven't been messing with
the setup. i am prototyping this system in an old truck instead of a
boat so that i can work on it more conveniently and get it all working,
then later i'll move it over. i don't have a TNC and have been hopeful
that i can use a soundmodem type of setup instead of a TNC. i haven't
seen a bit of this work yet! i'm just full of hope and optimism! lol.
the only thing i've actually done with the icom is use vhf/ufh and hear
a satellite using a yagi antenna, that's it so far! i was in the
middle of installing an icom antenna tuner and HF antenna on the truck
when i made that battery mistake, so i haven't even heard anything on
HF frequencies yet. i'm excited to get all of this working and gain
some real experience using it, i will feel a lot safer knowing i have
all of this available to me in addition to the usual radio equipment.

you can never have too many radios!