You will get a lot of opinions on this question, so here is mine: Go with a 60 lb or greater Rocna
or Manson Supreme. Why the Rocna or Manson Supreme? They have been proven to set very easily and hold very well for their weight in most bottom conditions
You will need at least 150' of 3/8" HT chain backed by another 100' of 3/4" nylon. Use one size larger shackles to compensate for the lesser working load of standard shackles versus high test. These sizes roughly match the holding power of the anchor witht the working load of the rode
You will be anchoring
in 6-20' of water
and 150' gives a 6:1 scope
in the deeper water
. The extra nylon rode
is for when the wind
is really blowing and you want more scope
for optimum holding.
That boat has a lot of weight and windage and will need heavy ground tackle even in the ICW. Oh and don't forget a heavy duty windlass
to haul up all of that weight.
As a spare anchor, the Fortress
is one of the lightest and best holding anchors. It's only downside is difficulty in setting sometimes and it doesn't handle a veering situation (reversing tide) well. Get a big one and set it up with 50' of HT chain (you can probably get by with 5/16" HT) and 200' of 9/16" nylon rode. You may have to haul this anchor up by hand depending on your windlass.