Small bolt to big bolt pattern

Aluminum adapters are avail' at ebay, 60 USD per pair. Fits your "easiest" and "cheapest" although "smartest" is debatable. Wheel adapters got a bad reputation many years ago, mostly due to improper mounting. They cant sit crooked on top of welded on drum weights. If they mount flat against the drum and torqued correctly they should be fine. Of course you would want a large bolt pattern spare and a different/larger lug wrench fitting the 20 larger lug nuts you will also need ( adapters all have 1/2" RH studs ).