Hello Mike62, welcome to the forum.. If you are located where you can purchase anthracite coal easily, I would forget about the wood.. If you want a system that saves money on fuel, and heats well. The real cost of cutting, stacking, cleaning up after, seasoning the wood, is very high. With coal,, just get the coal, and use it. The only thing you have to do is protect the coal from freezing rain and snow,, and this is only because it will freeze into a solid mass. The coal itself doesn't care if it is wet.
As far as I know, there are no true wood-gassification boilers that will also burn coal. The temperatures and gass flows are different, there may be some that 'can' burn both fuels,, but I'm not a fan of compromise solid fuel burners.
With a properly sized anthracite-burning boiler, for your application, an AHS 130 coal gun or AxemanAnderson 130 may be too small, so maybe the larger 260K btu versions, or a Keystoker KA6 would be better. If you want a hand feed, AHS makes a multi-fuel boiler, and Harman makes several sizes of hand feed coal/wood boilers.
You state you need 160K BTU, if this number is for really extreem cold weather, I'd recommend a smaller, slightly undersized boiler, like the AHS or AA 130 size.. they like to operate near their max output, and are very efficient. The use your LP to help make up if you have the rare very cold night.
With proper plumbing and controls the interaction of the coal and LP boilers can be automatic. The use of a big water storage tank is popular with wood burners, especially with the reverseflow and gassification systems,, because these systems don't work well when 'idling' or during ramp-up to max heat output, they smoke and still make some creosote. The water storage is an attempt to keep the boiler at efficient operating levels, then shut it down.. This is not needed with coal,, a stoker coal boiler idles very well and efficiently, then ramps up to max output without emissions or much lag at all.
BTW: I've been a wood burner for decades,, but now with coal,, I give away my standing dead, and dead-fall trees,,, they are a nusiance, not an asset !!
Hope this helps