You stated that your loans were unsecured. If they are cross-collateralized, then they may not be unsecured.
Although the issue has not yet been considered by the U.S. 4th Circuit Court of Appeals -- which controls bankruptcy law interpreted in the Maryland District, the general rule is that cross-colateralization of unsecured debts to real property is unlawful under the Bankruptcy Code, because it effectively creates a security in an unsecured debt, as a consequence of the bankruptcy petition filing, and without constructive notice recorded with the clerk or court prior to the bankruptcy. Matter of Saybrook Mfg. Co., Inc., 963 F. 2d 1490 (U.S. 11th Cir. 1992).
Were such cross colateralization permitted, creditors could effectively transform all unsecured debt into secured debt upon bankruptcy, and thereby render the entire bankruptcy code meaningless.
So, while I cannot be absolutely definitive, due to your locale in Maryland, I'd say it's a pretty good bet that the bankruptcy court will deny recognition of any cross-collateralization clause.
That said, if your bankruptcy lawyer determines that the credit union cross collateralization agreement is enforceable (or, more to the point, too costly to litigate, in comparison to the amount of savings gained by a favorable ruling), then your maximum liability would be the remaining equity in your real property -- which after considering costs of sale, appears from your allegations to be roughly zero.
Regardless, I don't see any legal rationale under which all of the "unsecured" loans would be considered immune from a lienstripping ("cramdown" using your terminology), because the HELOC and the 1st loan appears to render all of the other financing greater than the value of the collateral/real property.
Hope this helps.