Worship as You're Able, Even if it "breaks the rules"

Some time ago a friend of mine and I had a short discussion. I held to the idea that if Christians were stranded on a deserted island due to a plane crash, and only had access to coffee and donuts for use in the Lord's Supper, it might be acceptable to use these non-Biblical items in that memorial event. I said,

In such a case, I would concede that perhaps the spirit of the worship takes precedence over the "truth".

My friend objected strongly, saying,

We cannot substitute what we have because that is all we have. Truth is that Jesus used unleavened bread and the fruit of the vine. If that is not available, AND it is physically impossible to make it available the way to do it (as far as I can see) would be to worship 'in spirit' only. Since we must worship both in spirit and in truth and it is physically impossible to obey the truth, then we should only worship in spirit. We cannot start worshipping in spirit and untruth!! That would be disobeying what God said.

In reading the books of Chronicles, I came across a passage that seems to support my viewpoint. (I wasn't reading to "prove a point"; I was just reading, and came across this passage which seemed apropos.)

It's in 2 Chronicles, chapter 30. Hezekiah, a "good" king over Judah, cleaned up the nation, getting rid of idols and worship-houses for false gods, etc. He had the Temple restored, which had been neglected and had fallen into disrepair. He did what he could to get the nation back on track with Yhwh as their God.

He then invited all of Judah, and their sister nation, Israel (which was even more prone to idolatry than was Judah) to come to Jerusalem to celebrate the feast of Passover, which had been, like the Temple, neglected for years.

However, because of practical reasons, they were not able to celebrate this feast in the prescribed, "Biblical" fashion. They could not celebrate it at the proper time (at least until the next year, if they wanted to wait); the people weren't properly consecrated; the priests weren't ready; they doubled the time for the feast, carrying it on for a second week beyond the prescribed one week.

Hezekiah, realizing that not everything was "kosher", prayed. Here's the basic passage, starting in verse 18:

Hezekiah prayed for these as follows: "May Yhwh who is all good, pardon and forgive everyone who sincerely desires Yhwh, the God of our ancestors. Even—especially!—these who do not meet the literal conditions stated for access to The Temple."
Yhwh responded to Hezekiah's prayer and healed the people.

Later, 31:21 says,

Hezekiah carried out this work and kept it up everywhere in Judah. He was the very best—good, right, and true before his God, Yhwh. Everything he took up, whether it had to do with worship in God's Temple or the carrying out of God's Law and Commandments, he did well in a spirit of prayerful worship. He was a great success.

I wouldn't want to be dogmatic about it, but it seems to me that God is more interested in the "spirit of the law" rather than in the "letter of the law", at least in some cases.