Purpose clauses à la lettone

At some point in the past several years the allative la plus nominalization sort of unexaminedly became the standard way to form purpose clauses:

ni-lai lakoto la-ko-núkuki
1SG-return home ALL-NOM-nap
"I went back home to take a nap"

...or with a different subject in the subordinate clause,

ni-lai lakoto la-ko-ta-núkuki
1SG-return home ALL-NOM-3SG-nap
"I went back home for him to take a nap"

ni-lai lakoto la le Keoni ko-núkuki
1SG-return home ALL NAME John NOM-nap
"I went back home for John to take a nap"

I suppose this is plausible as an intuitive strategy, but I'm always suspicious of unexamined IE calques. This has been on my list to research properly for a long time. I still need to, but in the mean time I was recently reading a Latvian grammar and happened across a different structure that I thought was pretty cool. It uses essentially an imperative formation (Esperanto might call it volitive), and the purpose clause remains finite:

lai drusku atpūs-tos, mēs aizbrauk-s-im uz Jūrmalu
IMP a.little rest-SUB.REFL, we travel-FUT-1PL to Jurmala
"in order to rest a little, we shall go to Jurmala"

I wonder if the parallel Koa structure might work too, as an alternative to nominalization. Something like

ni-lai lakoto i vi-núkuki
1SG-return home FIN IMP-nap

Maybe? It's certainly nice to have options, and this new way feels a little more fluid and poetic somehow. One thing about this, though, is that it looks like a serial verb, but then the second verb seems to have different TAM marking than the first...which I think isn't typical for things called serial verbs? I'm also not sure whether we could have a different subject in the purpose clause:

?ni-lai lakoto i ta-vi-núkuki
1SG-return home FIN 3SG-IMP-nap
"I went back home for him to take a nap"

??ni-lai lakoto le Néliki i vi-núkuki
1SG-return home NAME Nellie FIN IMP-nap
"I went back home for Nellie to take a nap"

Actually I do seem to remember serial verbs sometimes having different argument structures from one verb to another, but TAM? It doesn't help a ton that my examples tend to come from pretty isolating languages without much tense marking. I need to review Describing Morphosyntax and probably Finnish, Turkish and Nahuatl while I'm at it...doesn't Finnish use some kind of translative suffix? Anyway, I'm clearly not prepared yet to offer an intelligent assessment here, but it's certainly interesting.