Attached below is a graph I use that shows the dates for solar longitude on Mars from 1997 to 2007. I copied this from some online report but now can't remember which one it was. Solar longitude tells the position of Mars in its orbit, 0°-90° is northern Spring; 90°-180° is northern Summer; 180°-270°, northern Autumn; and 270°-360°, northern Winter.
It is notable that Spirit landed in January, 2004 at the end of the period that the HEND instrument on Mars Odyssey indicates is the highest period of H2O deposition, Ls=270°-330°, which is early to mid Summer in the southern hemisphere:

47 - EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER
IN THE SURFICIAL MARTIAN REGOLITH BASED ON ANALYSIS OF
THE HEND MAPPING DATA.
R.O. Kuzmin, E.V. Zabalueva, I.G. Mitrofanov,
M.L.Litvak, A.V.
Parshukov, V.Yu.Grin'kov, W. Boynton, R.S. Saunders.
"As it well seen from fig.1b,c,d, two distinctive
"hollows" of neutrons flux reduction have been appeared
in the northern hemisphere during northern summer at
Ls=130°-170° and in first half of northern winter at
Ls=270°-330°, being extended from high to low
latitudes. At that, later "hollow" (Ls=270°-330°) is
characterized by much stronger reduction of the
neutrons flux and it traces from northern polar region
up to low latitudes in the southern hemisphere. The
first "hollow" is related with periods of the northern
middle summer, while the second one - with of the
southern middle summer. In both case the residual
polar caps serve as main source of the water in the
Martian atmosphere."
p. 2
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf

This is important because shortly after landing the Spirit rover observed material that might have been liquid water related, the famous "magic carpet":

Mystery at Gusev Crater.
By Leonard David
Senior Space Writer
posted: 01:35 pm ET
16 January 2004
"PASADENA, Calif. -- Scientists are puzzled about a patch of soil near the Mars rover Spirit lander that they now call "Magic Carpet". The intrigue has been stirred up by how soil behaved when the landers airbags scraped across the martian soil. That soil appears to have been peeled away."
...
"Sand and brine?
I think were seeing, already, preliminary evidence for a variety of materials, just within the soil," said David Des Marais, an astrobiologist from NASAs Ames Research Center. He is also a lead member of the long-term planning group that is charting future use of the Mars rovers, Spirit and the yet-to-land Opportunity. Finer grain material is seemingly globally uniform on Mars, Des Marais told SPACE.com. But then more coarse material is available locally too, he said.
"That darker stuff thats beneath the fines is a step in that direction. This funny peeling thats occurred, he added, could be, as hypothesized, the result of very fine grain material.
"But another thing that could do something like that, in my opinion, is a mixture of sand and brine," Des Marais explained."
http://www.space.com/missionlaunches/spirit_gusev_040116.html

Another possibility for what it could be is clay, since both Spirit and Opportunity made detections of clays with the mini-TES instrument.
Since we are coming into southern Summer perhaps the night time temperatures will be within the range that the rover can make some minimal movements. Geoffrey Landis explained the constraints on what the rover was allowed to do according to the Winter temperatures in his report on the detection of frost on Opportunity:

OBSERVATION OF FROST AT THE EQUATOR OF MARS BY THE OPPORTUNITY ROVER.
Geoffrey A. Landis1 and the MER Athena Science Team, 1NASA John Glenn Research Center, 21000 Brookpark Road, mailstop 302-1, Cleveland OH 44135; ****@nasa.gov
Lunar and Planetary Science XXXVIII (2007)
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/2423.pdf

This detection of frost was correlated to the observation of clouds over the rover site. It would be a good idea to estimate the time of evening the greatest deposition occurs according to when the nighttime clouds are densest.
The idea now would be to emulate how the airbag retraction discovered the "magic carpet" material. The period of highest water/ice deposition at Ls=270°-330° occurs this year from July to October. We would try to lay down a large flat rock over an area around the time of day the airbags were laid down, and uncover the area around the same time of day the airbags were retracted.
Ideally this flat rock or perhaps a shard of cemented sulfate would be as thin as possible to allow penetration of heat as happened with the airbag material to cause melting. Note also an important consideration often not mentioned about liquid water occurring in the low pressure on Mars is that an over cover of low porosity soil or a rock could supply sufficient over pressure to allow liquid water over a wider temperature range than normally happens on the Martian surface. This could well have been what happened with the airbags.
Other things we might want to emulate is similar thermal inertia properties of the area we wanted to cover to that of the "magic carpet" area. Or we might want to use an area consisting of salts or sulfates so that it would absorb large amounts of water vapor. Still another consideration is that we might want to use areas that approximate the thermal properties of the solar panels on the rovers since that was where deposition occurred on Opportunity.

Bob Clark