I'm afraid like Richard I too have a lift now.... age got to me here! but you can easily jack and support the Mog with a trolly jack and axle stands, and I have spent many a year doing so in limited spaces. Here's a method I found to be the best way.
Firstly a couple of short pieces of scaffold board are handy, couple of feet long will do. When you position the car where you want it jacked up position it with the rear wheels on the planks. The rear of the car is very low and the jacking point quite far from the rear bodywork and the planks give you that little bit of extra height that allows the jack to reach underneath. you will need a low level entry jack though with a reasonable amount of reach.
Parked on the planks? ready to start? now chock the front wheels, both sides. I'd suggest you buy a couple of plastic chocks as they're cheap and work! place the jack under the diff housing, its the easiest way and being a truck back axle its as tough as hell!
Now jack the rear of the car up. and when at your desired height place axle stands under the axle tubes or the chassis cross member which you will find just forward of the rear wheels. From the side of the car you will see what looks like square open tubes, this bar travels right across the car and is identical on the other side. The choice of position is dependent on what you are doing to the car.
When happy with the rear you can now raise the front. This you do on the lower tube of the crosshead. Do this in the centre of the lower tube. you will see that the central area between the upper and lower tubes has a cross brace welded in , shaped like an X. I used to invent all sorts of ways to spread the load along this tube and this might well be relevant on older cars but the later cars I have found offer no issues and the jack pad mounted centrally offers no distortion issues.
When jacked to the desired height place axle stands under the lower tube. Place them just outside the square central section about 2" from the weld points. I used or still use 6 Ton axle stands as they give a better working height If needed and are very secure. You can achieve his directly on the footprint that you positioned the car on.
Trad Morgan chassis' don't like being jacked up on just one side and certainly not on just one corner as you can damage the chassis. There is the other rear cross member that Richard described. On the roadster the rear underbody has an extended valance and this extends forward from the very rear of the car and at its front end is attched to the crossmember . This is at the rear of the fuel tank mounting area and you will see it changes into wooden planks. this is where you can also jack the car but you will need to protect the front edge of the valance.
