Thee's plenty of work you can do in PPSE in PRPNET. It's easy to set up, and manual BOINC credits are available.
There may be other short-running projects on PRPNet; I'm not familiar with all of them.
I suspect they'll be refilling SGS soon enough; so patience is also an option.
You could also do manual sieving, where you decide how much work to do. You could reserve two day's worth of work. Even if you don't finish before the challenge, you can always stop the sieving, and complete it after the challenge. There's no deadlines.
Also, with two days to go, you do have time to run something longer, depending on your CPU. Even my 10??? year old 1.8GHz Sempron 3000+ can do a TRP LLR in two days.
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