I like the first one for single axle trailer but... Only suited to 14-16" wheel diameters so no use for my 13" wheeled trailer (which is how I stumbled upon your post - looking for a good way to jack up the trailer).
I've long considered using a length of 4x2 timber along similar lines under the trailer frame but the angle for a deflated tyre would mean I'm unlikely to get it to anchor on to the ground to pivot the trailer up.
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets