The little sign by the cabin in the woods spelled out solutions from another age.

On chilly nights, it counseled, one had recourse to one's closet. When all the blankets and eider s were exhausted, it said, the guests should wrap up in his camel's-hair dressing gown, wind a sweater about his head, throw his fur coat over all and jump into bed.

Classy clientele, and well it might be.

This was president Herbert Hoover's place in the mountains. He came here from Washington a half-century ago to escape the siege of bad news during the Great Depression, which fouled his troubled term in office.

He bought 200 acres and had a cluster of pine cottages built in which he entertained friends and dignitaries.

Camp Hoover, as it is called today, languished after Franklin D. Roosevelt took office. It has been rebuilt and once again it serves as a retreat for dignitaries.

Unlike other VIP retreats, this one has no walls or fences.

"You're welcome to hike down there," said a ranger at Big Meadows campgrounds a few miles up the mountain on Skyline Drive. He even produced a mimeographed map showing various trails to the camp.

"We do, however, have guests this weeked," he said. "We ask that you respect their privacy. Please don't go peeking in the windows and try not to distrub any of them if you see them."

Fair enough.

Camp Hoover is approachable from a number of directions along a half-dozen walking routes that range from long and difficult to short and sweet.

We picked the short and sweet starting at Milam Gap about 20 miles south of the Luray Entrance to the Skyline Drive.

The walkway is called Mill Prong Trail. It descends from the drive for about two miles, first through gentle meadows and then through deep woods. About a mile down it crosses the Mill Prong, then follows this sparkling mountain creek for the next mile down to camp.

Along the way on a sunny Saturday we passed three clusters of hikers and two fishermen who had been testing the fish-for-fun stretches of trout water with fly rods.They hadn't had a nibble.

The mountain woods were still barren, but the warm sunshine offered promise that in a few weeks the redbuds and dogwoods would be flowering, as they already are in the Shenandoah Valley to the west.

We found Camp Hoover nestled in the triangle where the Mill Prong meets Laurel Prong and the two mountain brooks form the Rapidan River, one of Virginia's prize native brook trout habitats.

It was the trout fishing, in part, that lured Hoover 50 years ago, in the last few years Vice President Walter F. Mondale has tested the waters himself, and President Jimmy Carter stopped by for a look last fall.

Nice, then, that we commoners could walk about unchecked where presidents and kings have walked and cogitated, take a picnic lunch alongside the streams they fished in and enjoy the same sweet spring air they breathed

April is the beginning of high season for hikers and campers using the Shanandoah National Park, which is an easy two-hour drive west from Washington.

Back-country camping is permitted anywhere in the huge park, as long as campers stay off the main trails. Last weekend a few tent people were already pitching camp at wilderness sites, and along the Appalachian Trail long-range trekkers were hoisting their burdensome loads.

These are poeple who already know their way around. For those who don't, the Potomac Appalachian Trial Club offers an excellent book that explains how to get ot such places as Camp Hoover and back to civilization without retracing one's steps.

It's called "Circuit Hikes in The Shenandoah," and lists 22 walks through the woods.

I've done five, ranging from an exhausting haul up craggy Old Rag Mountain to a spectacular if crowded jaunt along the crashing waterfalls of White Oak Canyon.

Those two are among the most popular hikes, but the book has a number of less-traveled routes like the Mill Prong Trail, where the scenery is just as satisfying.

For more adventuresome travelers wishing to plot their own courses, the park offers topographical maps of the north central and south portions in which all trails are shown.

Wither way, May is prime time to head for the hills.

For copies of "Circuit Hikes in the Shenandoah" send $2 to Shenandoah Natural History Association, Shenandoah National Park, Luray, Va. 22835, or to Potomac Appalachian Trail Club, 1718 N St NW, Washington D.C. 200036.

Maps are available at $1.50 apiece from the same sources.