You might be doing some things yourself if you can't find a qualified contractor. I tried to pay someone to fix our house, but there just wasn't anyone I would trust available for at least a year. Now the folks at the lumberyard think I'm a contractor. Look up the formulas, crunch the numbers, figure out what you need and then go from there. These guys are probably busy as hell with these crazy storms, heat waves, and all round unusual weather (cough cough). You might be waiting, but it will be much easier to get the bid if you do the numbers and tell them what you want. Contractors are always going to drift towards what makes them the most money. Clearly the first bid wasn't done for your sake, but rather that contractor probably won't do any job under $40,000 due to his overhead. Put yourself in these guys' shoes; there are dozens of customers out there who will just give them a blank check and say my house is too hot/cold. That's nothing but a payday and no headaches for a HVAC contractor. You on the other hand care a lot more about this project than most clients and will be managing the whole thing every step of the way. If you come up with a plan of action before they get to your house then you will have a much easier time of convincing these guys it is worth their time.As they say, "Welcome to Idaho, turn your clock back 20 years," I haven't a clue who I could get to do these calculations. I can barely get people to show up to make a bid.
The two air to air contractors who showed up thought 3 ton was more appropriate than 4. My big problem now is that the insulation contractor went missing. Batts I can stuff, blow in I can blow, however I have only been able to find one person who does closed cell foam. I do not have the equipment for it.