I'd rather spawn Nunyunuwi than Senmurv. Senmurv can be over 4 hours of your day waiting on Cerf's Up to respawn, especially if you can't find players willing to clear Special Tarasque Force when it's up.

I've never had problems getting people to show up for Nunyunuwi spawn parties, even at 3am. A quick message to all my linkshells and the server hunt Discord would draw at least 2-3 people, and there were times enough showed up to form a couple of parties. There's usually someone leveling an alt job that's happy to get the FATE XP.

If you're insistent on doing it solo, wait for 5.3. It wouldn't surprise me to find people solo spawning with a single character once they can fly in the zone since that will reduce travel time quite a bit.