To do that though, you would have to have a CB on said electors or their Allies, or take bad Stab & W.E. hits.
When it's the difference between becoming HRE and not, it's worth 2 stab & WE.
Yup. Plus, it's pretty easy to get a CB. If you don't border them and thus can't Fabricate, just loan them some money. Take a look in the Ledger to see their monthly income and current balance, and loan them 5-10x their income. If their income is 20 gold, loan them 150 or 200 or so. 12 months, 8% interest.
Most of the time they'll renege, and you get a CB at a modest gold cost. If they do pay it back, just loan them again until they don't.
You can often also trick them into giving you a Trade Dispute CB. Embargo them, and they'll normally Embargo you straight back. A little while later, cancel your embargo. They're often slow in cancelling theirs, giving you a window of a week or two during which you have the Trade Dispute CB to use against them.