Wine kit in two 25l FV (air space etc)

[techtone]

I have my "Reserve du Chateau Wine Kit Chilean Merlot" (30 bottle) in primary ferment. I have two plastic 25l fermentation buckets which I also use for beer. I do not have a demijohn/carboy. I see plenty of wine starter kits with two 25l buckets.

I am looking at the instructions and it seems important to minimise head space after degassing. (hence the demijohn) How do people do this with 25l buckets? Or is not important unless long term bulk ageing?

I have a polypin which I intend to use for dispensing the finished product and had considered using this after degassing and then (when cleared) siphoning out to a bucket temporarily, cleaning polypin and siphoning back. However if this is not necessary it will make it easier?

The instructions say degassing could take between 1 hour and 3 days but then to IMMEDIATELY avoid head space! Again, is a large head space of a 25l FV ok during degassing? I do not have anything fancy (just long spoon) to degas so it might take some time, especially being at the lower end of the temperature scale, however dispensing from a polypin probably makes degassing 100%, slightly less essential as it will come out naturally over time??