I have put up three different Dandy types solo.
High Side Destiny (fridge, but no toilet) - no fun on your own, but possible. Mine had gas struts on the sides, but not on the beds. The hardest bit is getting the bed stays in place. On the destiny, they locate onto pins on the corner steadies. I found that after lifting the bed over, I would get under it facing away from the dandy and grab a support in each hand. The weight of the bed is taken on my back and I can lift it slightly to get the stays over the pins. I found aiming for both together better, since getting one in an the going for the second always seemed to dislodge the first. The side walls were easy as you could open the door while the wall was down and step inside to lift...the gas struts also helped! Getting PVC trapped in the hinge at this point was annoying, especially if you didn't notice and had to take it down to this point to free it. I also found the assembly where the support for the PVC section locks into the side wall awkward. It didn't seem to be any better from inside or outside. If outside a step is required. If you don't notice this is wrong until later it also annoying.
Putting it all away, the worst bit seemed to be pulling all the roof material out when it gets trapped under a bed. I mostly used the roof on top method rather than folding it inside. Folding inside neatly solo was a step too far, but did make subsequent erection easier.
High Side Destiny Awning with extended annex - you have no idea how hard this is solo.....The zips for the sides were so stiff. the only option was putting it up as a single piece was the only option. I also had poles that had lost there springs, so they tended to come apart withthe slightest knock until all was in place. The strategy was to get the main frame up, then the annex frame. Keep the front low and get the awning up on the front (queue pole split here as the retaining springs are broken). Gradually work it up the frame until you can tie it off inside the dandy. I only put it up three times, the worst was in the rain and it took over two hours to get the awning up. It does not help that when you get close to the Destiny pulling the awning further requires a step to stand on.
Dandy 4/5 with inboard wheels. Having sold the Destiny and finding regular tents uncomfortable, I bought another Dandy. The 4/5 was so much easier to put up on my own. The beds may be the same size, but you are dragging so much less roof. Others have covered tips for the rear entry models. The only thing to add would be don't put the 4 bungee loops for roof/bed in place until you have the bed ends up. A little slack helps a lot here. I found that I could pull up the door side using the PVC and then there was enough friction with the roof to keep it up until I could free the hoop strings and lock on the hoops. I would then go inside the Dandy to lift up the kitchen wall, put the centrl pole in then go round, release strings and lock in the hoops. The real bonus is with a 4/5 I don't have to stand on a step to reach anything. The Destiny needed a step.
No Dandy awning with this one, but a variety of alternatives. The Trio 123 with some extra poles from another had the best fit. The Movelight would have fitted if modified with drats, but since I was planning to raise the Dandy, I could not modify until the Dandy height was fixed.
Dandy 4 with outboard wheels. Bought this one as an alternative to a full rebuild on the 4/5. It was in really good condition and had both a Dandy awning and an underfloor heater. So far I have only put this up twice, and it seems harder than the 4/5, but only marginally. I think I need to adjust the hoop string length to get a better hoop angle. I did this on the 4/5 and it made a difference. At the moment the non-extending hoop has fallen down towards the bed end each time which then results in difficulty getting it back up as you have to feed the roof material over rather than just pull it back up. Longer strings would allow it to go further past vertical and stop this. Other than that, the 4 is similar to the 4/5.
Compared to the Destiny awning, the smallest Dandy awning is a breeze. I have only put it up once as a test, since we have not yet gone away in the new one. Using the frame first then pull the awning over from the front technique worked well. It helps that all bar one of the pole strings are present, so the poles don't come apart. It took just half an hour for a 'first time' erection without looking at the instructions.
Note: Always remember the bed bolts.....dealing with an escaped mattress is a two person job.