I'll tell you what Cameron, I underwrite commercial loans all day long and a loan with the rate you speak of is unheard of. A business owner with any business sense at all would spit in my face if I offered him a loan at 10-15%. And to boot a commercial real estate loan would never have a maturity of 50 years.
We are writing variable-rate loans at under 3% and fixed rate loans at under 5%. Loans will may have a 20 year amortization but they longest we'd go in time is 15 years. A 20 due in 20 is an exception and usually seen when going through the SBA.
It is obvious that our OP and the person who wants to snake him don't get it, otherwise he would have gone straight to his CPA and not to this message board.