I have always enjoyed your clips and how you manage to find really strong fit girls to do the lifting. Moreoever, I think it is really cool that you managed to find Varya Akulova to do some lifts!
Since you write that you are running out of ideas, let me give you some tips that might help your sales or production when doing your next videos:
1. If possible, try having the girls wear short pants and tank tops. It just makes the video so much more interesting when you can see those thighs and arms. You have already managed this with some of your videos and those are the ones I love the most.
2. When she lifts you, piggyback or shoulder ride, try having her flex her muscles and you *squeezing* them. The touching/squeezing is the important thing here - this is little act adds so much to the video because she is lifting you + flexing + you are squeezing/enjoying - all at the same time!
3. Do more endurance lifts, where she carries you as long as she can. In the case of your models, they are really strong and can probably do this longer than most. My experience in getting lifted is that the girls get faster uncomfortable with keeping one single carrying position (like shoulder hurts in shoulder ride or arms get tired in piggyback), and that she can carry longer if you can switch positions on her. After a little training, it really isn't hard to switch positions for a rider from piggyback to shoulder and back. Piggyback --> shoulder: just have her bend and put her hands on a tree or wall, then you climb up and she stands straight again.
Looking at your models, I think you can probably do 2-3 switches with them like this and have them carry you for a much longer time, which will make your videos much more valuable!
4. Videos filmed from the point of view of the rider are good, and sometimes maybe the only way if you are alone with her. But really, unless you have a very wide angle lens, a lot of the body shape and character gets cropped away. This might be my personal opinion but I prefer a tripod shot where you go far away from the camera, rather than a on-board view that is cropped and you cant see much. One solution could be to have two cameras, one at each end of the course where she is meant to carry you. You dont need fancy cameras nowadays; 2x regular good smartphone camera is better than 1x professional camera from far away.
Just a couple of tips from a loving lift-n'-carrier fan, thanks for your work so far!