Although a lot depends on actual figures--- such as how the operating costs on your patio home compare to the operating costs on your current home--- what you hope to do may be workable. I say this in spite of generally encouraging down-sizing for retirees rather than upsizing.
With $885,000 in financial assets and a need to draw only $20,000 to cover taxes and insurance, you withdrawal need is only about 2.3 percent of your portfolio a year. That amount will be reduced still further when your wife starts collecting Social Security.
Now let's factor in the larger home purchase. You'll need to take about $240,000 out of your IRA over some period of time to have the extra $200,000, perhaps more. In addition, the operating expenses of the house are likely to be about $8,000 a year greater than your current house. As a consequence, you'll be drawing $28,000 a year from about $650,000 of financial assets, or about 4.3 percent of your portfolio. (Less the future Social Security benefits.)
That doesn't leave a lot of margin for you but if owning a nice house is a major pleasure for you, it's a reasonable thing to do.
You and your wife might also benefit by delaying your Social Security benefits and drawing down your financial assets because you'll get more increased income from Social Security than you'll get from your investments. I've covered this in a number of columns, all in the "Social Security" category on the website.
Scott