Hello.
I'm a newbie affiliate (but not very newbie).
I'm not an expert to advice but here is some of my experience.
I'm also having hard time to make profitable campaign with sweepstakes.
Here are 2 things you may also consider.
1. conversion scrub
I heard of that conversion scrub is common especially with email submit type sweepstakes offers.
Conversion scrub means that advertiser only pays you 1 conversion when there are 3 conversions for example.
They say they reduce conversion rate if the traffic quality is bad.
But, it is true that they can adjust conversion rate at any time.
What I personally expect in the future is the affiliate network run by blockchain tech.
I heard that decentralized blockchain tech will eliminate all of these kind of shady conversion srcub that is occurred in the middle.
I remember few decentralized
affiliate networks were established few years ago but it seems that they were closed when bitcoin price drop
There are few websites that seems still alive.
Run ads around the world at the best prices
ubex.com
Explore, list and promote on the world's first referral marketplace for all tokenized assets
attrace.com
But I would not use it for now because it still looks very early stage so there might be various issue.
2. click loss on tracker
I wonder what tracker you use.
In my personal experience,
Voluum has the minimum click loss rate.
Low click loss rate means higher ROI.
If your campaign has -20 ROI, it can be changed to +20 only by reducing click loss.
You should check both of visit number in the tracker and traffic sources.