I understand. I guess the 1 hour per day is in case it’s a ‘big’ project (350 contributor hours) in the shortest coding period (12 weeks). But we could also go for the opposite: a small project (175 hours) over a longer coding period (max. 22 weeks). That would boil down to about 8 hours contributor work per week - meaning less than 1 hour mentoring per week. And there’s a flexibility in terms of planning ‘weeks off’.
Then, there’s also the flexibility to share the mentoring role. I would like to take up the mentoring regarding the project (esp. during the ‘community bonding period’) and UX/UI. So we can share the burden.
Ouch, yeah, that’s something we really don’t want. That’d be a grand waste of time for everyone.
Just to jot down some ideas - some from what I believe are popular requests, some from my personal wishlist 
- Rewrite database back-up & automation [#5099 & #4850]
- Episode listening without subscribing (incl opening shared episode) [#4710]
- Upgrade ‘New’ screen to ‘Inbox’ [#5267]
- User-definable queues [#2648]
- Nice empty-state screens, other UI refinements
- Rewrite of auto download/deletion (including oldest to newest, keeping N newest) [this milestone]
- Revamped discovery screen (to be seen if country-based suggestions possible with PI’s - support for tag/topic filtering (even based on iTunes) would be welcome) [#4747, might also cover #5373]
- Experimental/Optional bottom bar navigation [#4376]
- Support for Transcript tag [#4935] & related enhancement of player screen navigation [on forum]
- Time selector in statistics [#5102] + ‘your year in review’ as added bonus
- Episode-based notes [#1946]
- Multi-press hardware buttons (e.g. to fast forward) [#2715]
- Continue playing when initiated from Podcast or Tag [#1533]
- Integration with more synchronisation providers (Podfriend, contribution to Nextcloud Podcast app if maintainer agrees)
Some more Podcasting 2.0 stuff:
- Further increase chapter support (button for ‘more info’ link)
- Cross-app comments (based on ActivityPub protocol)
- Support for Alternate enclosure tag
- Support for Person tag (mainly episode/podcast search)
I guess this is plenty to fill 175 hours 
I realise that some of the above points would need decisions and/or mock-ups first. But if we know what we want to ask the GSoC contributor, we still have a few months to discuss them 
I think we should make a decision latest the coming weekend, so that we have a week to prepare the application (determine the project ideas).