Mike,
You've asked some good questions, hopefully I can shed some light on it for you. Sometimes you have to use propane if you don't have wood. I live on the prairie so I use propane.
1. Yes
I've found that turkey fryers or like your camp stove, the burner has an effective range of 11" diameter. So if everything is centered than you would have a great deal of dead space. The sap will get piping hot in these areas, but you will not be using your pan as a continuous flow then, rather batch boiling.
2. Good start. Vast amounts of heat are lost out the sides, anything to retain the heat will only help. But please use ***caution***. I have said this in every response to someone that uses propane, so here is your on PSA. Excess heat will make any propane hose soft, pliable, and they will burst. I've had a near disaster.
Burners.jpg
On mine I used turkey fryers, each one 11" on center. I run a 2x4 SL continuous flow. Hope that helps a little.
SDdave
It's not the size of the tree...it's what inside that counts!