At home, lay your sail out on the ground and attach a loop of 2mm rope to the material in the top of the sail that holds the male mast plug. There should be enough room to have the rope laying off to one side of the mast plug, not disturbing it. You need about 50 mm of 2mm rope length from the top of the sail to the figure ???8????? knot you tie off the 2mm rope with.
Also purchase a cheap screwdriver which is about 30cm long and a cheap hammer.
Before de-rigging, pound the screwdriver through the loop at the top of the sail (best done with the side of the hammer, just in case you miss the screwdriver). When the screwdriver is fully into the ground, walk around the sail, undoing the outhaul and the boom. Remove the boom from the sail.
Walk to the mast end of the sail and SLOWLY let off your outhaul. When the outhaul is fully off, twist the mast back and forth, at the same time pulling the mast out of the luff sleeve.
The mast should come straight out of the sleeve. At the same time none of the monofilm panels should be crunched up, preventing your creasing problem when de-rigging.
The length of the screwdriver usually will hold the sail, even in sand.
I have a variant of that which is somewhat more permanent than a piece of line, as long as there is a section of webbing coming out of the masthead (like on most of my sails).
What I do is use a flame to heat a nail or something and burn a hole through the webbing, about 5 cm from the end. Then, using BRASS grommet rings and grommet setting tools, pound the grommet and form it into the hole in the webbing. This will provide you with a permanent hole in the peak of the sail with which to use a stake (or phillips head screwdriver) to anchor the peak of the sail while you extract the mast. If you have a friend to help de-rig, you don't need these tricks, but if you de-rig yourself, it is simply NOT POSSIBLE to get the mast out without excessively folding / crinkling the sail. This is where 85% of the cracks come from; another 10% come from inadequately rolling the sail into a tight bundle for storage; a mere 5% come from use / misuse on the water (my rough guesses on the relative percentages).