"my next thought is to go with an outdoor boiler"
and
"I have more wood than I could ever burn"
and
"I'm starting to think about when I'm old"
Outdoor boiler may mean you need >2X the wood. Or more, depending on who you ask.
Just moving it around when you are "older" could be quite a task.
The only people I ever knew who were happy with outdoor boilers either just paid for the uninstalled thick-wall CU, or never used wood for heating before.
For supplimential heat, might look into bagged or bulk small coal and a small burner.
A ton of decent coal is a whole lot of heat in a reasonably well insulated house.
Might try calling dealers around Clymer (sp?).
All I know for sure is when they were complaing about the cost of coal being $350, I said "Yea! My last bill was almost $300 too!"
They meant for the year, for coal
I meant for the month, for nat gas.
G-