I'm not quite certain that the P&P cruise is worth its money ATM. You're correct in that it is extremely difficult (impossible?) to see the projections in HEA on the P&P cruise. Most people who have done the cruise since HEA debuted have complained that this has ruined the experience of watching the show. Being that HEA is a product of the new technology that's developed since Wishes was debuted, the projections have been incorporated into the show so much that it becomes the primary element of the "story" that show tells. P&P was not meant to view HEA, it was meant to view Wishes-- which didn't rely on projections on the castle. You may enjoy watching the fireworks and listening to the soundtrack, but without being able to see the projections, you'll lose that key element. In addition, recent reports have complained about the quality of the snacks that they've received. I would encourage you to read
this thread, where someone who recently attended it laid out their complaints.
Provided that you haven't already done so already, if I was in your shoes, I'd book the MK dessert party for HEA instead. My family really enjoyed it when we booked it back in 2015, and as someone with experience touring the parks solo, I could see myself enjoying it even more as a solo traveler. Hope I've helped.