Re: Sunlight and Storage
If you do not have any other choice, ge a nice bottle of Aerospace 303 protectant, apply product to penetrate well into fabric pores, dry well. If in plain summer with constant water use at beach, lake, pond or whatever, will need to inflate all chambers less than in winter time.
Sibs/ribs usually are inflated to minimum 3.0 psi or 0.20 bar. If you leave boat inflated to that pressure in plain sunlight the pressure will rise beyond 4.0 psi or more, a good thing to do will be to inflate boat very early in the mornig to 2.0 psi and take a pressure reading by noon to see what is the max pressure achived. If it's between 3.0 to 3.5 psi it's ok, this max 3.5 reading is the factory recommended working pressure for any inflatable.
As I'm not the weather man can't tell exactly what minimum pressure to inflate your boat, it's a trial under sun issue, will need a pressure gauge for this test. If with available exterior space, you could leave the boat's bow & transom suspended by means of 2 horizontal wooden slats resting on a flat surface and place a thick canvas open like tent to shade the whole boat. Don't leave unshaded boats lying on cement floors or sand in plain summer sun as temperature will rise to unimaginable levels.
PD: Have not specified if the boat/engine combo will be left on top of a trailer, anchored at sea and that makeas a big pressure difference to account.
Happy Boating