Can a Deed of Trust be modified without the consent of all parties involved?

You will need to consult with a real estate attorney in USVI.

I suggest you consult with an attorney who handles commercial real estate transactions. I suggest you as what charges you will be responsible for - water, heat, electric; what alterations are allowed; what repairs will the landlord cover; if the landlord will abate rent for COVID shutdowns.

If your lease doesn't allow a sublease, you can't do it. I'd just approach the landlord and see what could be done. If the person moving in would be willing to sign a one-year lease and do the typical background check, the landlord may let you out of your lease.

I suppose it doesn't matter if you have the lease giving you permission and the lease is long enough to justify the building expense when you won't own it. But I'd buy the land so you could eventually sell the property with the building on it.

Did you purchase the property before or after the fire? If before, did you have insurance? If after, what was the agreement you had with respect to the insurance proceeds the Seller was to receive? The Warranty Deed is what is offered when there is a transfer of real estate and the seller warrants ownership to another. Frequently this will also involve title insurance to back up the warranty deed if there were other claims against the property