I feel for you, not everyone has a scott, RSI, or slim in there area to install. Its really showing that many dealers will push whatever they have left in their inventory , regardless if it fits. Sounds like a pyramid scheme by the manufacutrers. Too many bad dealers are giving the good ones a bad rep.
However, IF you have to make your system work, I posted a link from Siegenthaler on wood boiler applications. There are many picture diagrams and full explanations of equipment and controls and staging with storage. Using storage actually makes your system more efficient anyways. Anytime you reduce or eliminate idling , it save wood. A simple 120 gallon tank will work , it doesnt have to be huge. I would suggest a full calculation of X # of gallons would do for you. Most of the indoor boilers are 60-200kbtu size and they heat 500 gal in 4 hours flat out gasing. This is recover time not cold start. 160 on and 180-185 off. several of those 1000-2000 gal storage heat the house for 2-3 days without firing again. The LP tank doesnt have to be indoors and it doesnt have to be pressure. Some are just framing a box around it and spray foaming.
Anyways even if you dont keep the hawken, the storage will work with anything, and its easy to sell off. Youll see storage equipment and controls dont last long on CL or the forums. good luck