Maybe train for it the same way you might if you were building up running distance perhaps?

So you can do 30 mins hard no worries and 1 hour easy now and you have about 6 weeks left you might do something like the following. Take Thursdays and Sundays off any skipping. Still it's not much time for the gradual no more than 10 % increase that would normally be recommended.

I think shock to the joints is likely to be the biggest killer. I've done long distance bike rides without much preparation and felt OK (although I'm a transport cyclist - but don't hold that against me!) and 12 hour canoe marathon and felt OK but throw in running with a bit more shock (although also more competitive) and it hurts. Maybe focus on landing lightly especially if you're a big guy? Check that the surface you are skipping on is safe too.

A lot of people are defeated when doing long distance running by their own heads too. A mental strategy to keep you going might help. Like music and conversation. Now I'm used to endurance stuff I love to zone out and think about pretty much everything and it's part of my stress relief but until you are used to it the boredom might have you making it harder for yourself and feeling more tired than you really are.

Also I'm not sure how your shoulders will go. It's a bit impossible to prepare with such little time in a way that's not going to hurt and can guarantee no injuries. Maybe do lots of stretching? Where it says w/up I would skip slow so it's still continuous 30 mins but might want to do some sort of pre-skip warm up and stretch too perhaps? Still stretch on off days too. Good luck :-)

Monday                  Tuesday
easy 30 mins      fast intervals short session
week 1 v slow 30 mins   10 min w/up 1 min at 3/4 pace, 1 min easy X 5, cool down
week 2 v slow 30 mins   10 min w/up 1.5 min at 3/4 pace, 1 min easy X 4, cool down
week 3 v slow 30 mins   10 min w/up 2 min at 3/4 pace, 1 min easy X 3, cool down
week 4 v slow 30 mins   10 min w/up 1.5 min at 3/4 pace, 1 min easy X 4, cool down
week 5 v slow 30 mins   10 min w/up 2 min at 3/4 pace, 1 min easy X 3, cool down
week 6 Easy week - no sessions longer than 1 hour

Wednesday                       Friday                                                          Saturday
steady skip fast intervals short session                                                 long
40 min        10 min w/up 30 sec hard, 1min easy X 5, easy 5 min cool down 1 hour
1hr 10 min       10 min w/up 30 sec hard, 40 sec easy X 5, easy 6 min cool down 1.5 hr
40 min        10 min w/up 30 sec hard, 30 sec easy X 10, easy 5 min cool down 1.5 hr
1 hr 30        10 min w/up 30 sec hard, 30 sec easy X 10, easy 5 min cool down 2 hr
1 hr 10        10 min w/up 30 sec hard, 30 sec easy X 10, easy 5 min cool down 2.5 hr