I have the following segments booked and paid:

UA4299 DCA - EWR 18:00 10 Jan - 19:21 10 Jun
UA 568 EWR - IAH 21:19 10 Jan - 12:09 11 Jun
UA 201 IAH - GUM 09:45 11 Jan - 18:00 12 Jun
UA 183 GUM - MNL 18:50 12 Jan - 20:45 12 Jun

UA 184 MNL - GUM 23:35 13 Jan - 05:25 14 Jun
UA 200 GUM - HNL 06:50 14 Jan - 17:55 13 Jun
UA 218 HNL - ORD 19:25 13 Jan - 08:29 14 Jun
UA 608 ORD - DCA 09:51 14 Jan - 12:42 14 Jun

All indicate a fare class of L. On the UA site I am offered the chance to upgrade the first four Xor the last four segments at a price of USD$600.00 PLUS 30,000 MP Miles. Xor I can upgrade all eight segments for USD$1,200.00 PLUS 60,000 MP miles. No other option is offered and most of the segments are listed as 'waitlist only'. I don't want to spend those kinds of resources on this set of flights but I had a passing thought that it would be nice to try out the Global First product on a single segment. I have no status, though I could by silver. I don't think that would be of any help. I do have the MP Explorer card and the old CO OnePlus card. Which I also do not think will help.

Is there a cost effective way of attaining an upgrade on a single segment to the Global First cabin?