Considering everyone on PM is using unlocked phones and most are quite tech savvy, I really think you need to compete better for USA roaming rates. Unfortunately your options don't compare well to something like roam mobility. Therefore why would I use this compared to just sticking a roam mobility sim inside my phone. Roam mobility costs $5 a day for 500mb of LTE (and unlimited data at slower speeds if you pass 500mb). Also unlimited SMS and calling USA and Canada.
If you came out with daily/multi day options which compete with others such as roam mobility, more people would use it.
Maybe something like 500mb + unlimited calling and SMS = $10-12 for 5-10 days, and just raise price based on different amounts of data. However you can determine pricing structure that makes sense yet competes better.
Edit: I just noticed there is a talk text and data bundle 250mb for $20 good for 10 days. This is the right idea but still cost prohibitive based on easy alternatives, and what if I only need a couple days or 5 days.