Proton is excellent service, but has quite limited free tier. The thing is that Proton Unlimited plan (quite costly, but worth every cent, believe me) combines SimpleLogin Premium plan (btw, its owned by Proton) with the richest set of features available from Proton for single users.
Plus, you pay once (for Unlimited plan only), SimpleLogin Premium is included in Unlimited.
To answer you question: Id go with 1. With slight modification though: use SL for everything except banks.
Im on Proton Unlimited and thats how I use it.
On Premium plan, its allowed (or am not understanding you)