I' from seo background and just started venturing into paid traffic. Just hit my first profitable campaign after months of trying, and I focused only on my geo since I know the culture and stuff. That decision has paid off for me.
I'm looking at sweeps offers that have like $10 payouts in AU and the like, and I'm wondering how much harder is it to be profitable in those geos? The terms seem to be very strict whereas it's much more lax when operating in my local geo. Do you need a cloaker for that? I'm being very aggressive with my landers and can't imagine getting profitable where the terms are so strict.
English is my second language so no problem there, but the strict environment is something that prevents me from taking action.
What GEO are you currently doing well in? Are you just using a landing page to promote the sweeps offer or are you just direct linking to the campaign? There are a lot of factors you have to consider but the main thing would be to have a tracking tool to see what works and what does not work with new GEO's. from my experience sweeps in AU/NZ do well but like any campaign you need to be able to optimize the traffic for best results.
Its not really harder, its just more expensive and you need bigger balls to run these 
With low paying offers, you see conversions coming in after you've spent a few bucks. Lets say you've been running a $1 payout offer, now multiply it all by 10, do you have the balls to wait 10 times longer in terms of ad-spend? 
Im running high paying PIN submits, some close to $20 per conversion but its not funny sometimes 
The best advice I can give you, whitelist the placements on low paying offers, then switch the GEOs and test just the whitelisted ones.
Creatives for pins are the same, maybe an additional sentence explaining the flow. The traffic you need to buy is a different ballgame.
Need to master the process of finding / buying / filtering carrier traffic.
BUT you'll find yourself in a dogfight with every other mobile affiliate.
Plugging in Tier 1 Popads with carrier filter will not fit the bill.
Buy in bulk and monetize the redundant wifi traffic at break even or small loss, or find untaped traffic sources, or go tier 3/4 (payouts will be more in the range 2-5$).
As sebastian_r told you, for PINs you need carrier traffic, for CC submits or email-submit sweeps you dont. So plan carefully what you want to transfer where.
Running a slightly modified LP on high paying offers can work if the offers match in some way. So yup, the example you mentioned could work : first test the "low paying iphone sweep" and then run the "win iphone CC submit" on whitelisted placements. The idea of using a low payout offer first is simple, you test two things this way : whether the placement has traffic responding to the angle/prodcut and you detect bot placements too. So once you switch to the high payout offer, you at least push it to real traffic and not bots.
It never stops surprising me how simple and common-sense this stuff is, and that it actually works
I keep wanting some super elaborate scheme that will make a ton of money.
There is one point that hasn't been my experience - WiFi has worked out for me w/ pins on pops. This is for t3 countries only though and I ask the user his carrier and redirect based on that - if I were to target carrier only volume would be super low so I tried it and it has worked. Even accidental tablet/desktop traffic has given a few conversions here and there:
Campaign 1:

Campaign 2:

Both these are carrier billing PIN submit campaigns
And thanks again Matuloo, without you prob I wouldn't have had these slightly profitable camps going! 
I just noticed that carrier is more profitable, but what's the difference to the user whether he's on WiFi or carrier if it's not a mo-flow? Does he feel safer when submitting his cc/number when he's using the carrier interwebs than if he's using a WiFi (possibly a public non-secure WiFi)? This always confused me!
Another follow-up question if you don't mind: Is the carrier/WiFi gap even bigger on mobile display than on pops? Or - is the gap bigger on higher payout PINs than on low ones?
In determining what offer to run - or not run - never let your decision depend on just the payout. Offers that pay a high payout do so because 1) the conversion process is longer & harder and 2) probably the user needs to pay. What is important in determining what offer to run are the following factors:
1. eCPC and eCPM. Ask your account manager about what offers are currently performing the best. Sometimes an offer with a low payout will outperform an offer with a high payout. Its all about the conversion!
2. Relative payout comparison. Compare the payout you are getting with the payout you can find for that specific offer on odigger.com and offervault.com
3. Fit and alignment between the offer and your traffic source. Offer and traffic source need to complement each other.