Sealant/wax combo also works for me but not exposed to the low temperatures you will encounter.
I usually apply sealant followed by wax. Poorboys are my polish of choice. Often followed up with Poorboys Ex-P but that's probably too lightweight for your needs. Always topped off with coats of a good wax. If pushing the boat out maybe a glaze too after sealant but before wax.
Sealant wise, Gtechniq C2V3 is favoured by quite a few on here. As a top coat, it's supposed to be applied over wax but some favour it applied onto bare paint (polished) then wax over top. Personal choice and a bit of trial and error I guess.
Jetseal 109 is good stuff
Sonax Xtreme Protect & Shine Hybrid NPT
DoDo Juice Supernstural Hybrid Paste Sealant (a half wax, half sealant product)
Be aware that some sealants and coatings need to be applied onto panels above a certain temperature. For instance some Gtechniq stuff needs to be applied to panels between 20-30 degrees but some can be applied at temp as low 5 degrees.
Wax suggestions:
Collinite 915; 845 or 476s
DoDo Juice Pro range hybrid waxes
DoDo Supernatural wax
I guess if you want to go all out then: polish - sealant - wax - top coating, e.g. c2v3