Aviation has a relatively low percentage of total emissions only because globally almost nobody can afford to fly. For a rich person like you and me, a transatlantic trip is a good way of doubling your emissions for the year.
You could probably make that up by driving less, since a typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year. If you look at the UK, it's estimated that 20% of the nation's emissions are directly from heating and hot water, which is analogous to many areas of the US. This is largely due to old and poorly insulated housing stock.
This isn't meant to be CO2 whataboutism, but rather to compare meaningful individual contributions to emissions. IMO aviation for most international travelers may be a large single contribution, but they do it infrequently and other activities could be moderated of modified to make up ground. I mention this to support my parent claim that aviation has numerous benefits, and they may likely outweigh their costs accounting for externalities. That said, I would advocate a carbon tax that prices emissions into things like gas, heating, flying, etc.
http://www.kimnicholas.com/uploads/2/5/7/6/25766487/fig1full...
There's really no budget for burning kerosene if we are serious about the 1.5 degree target. The only way I see aviation being compatible is if there is a massive breakthrough in biofuels or battery technology.
[1]https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15...
What about taking a normal person and not an American? Even compared to other developed, Western-type nations, the US emissions are terribly high (only matched by the other 2 large Anglo-Saxon colonies); but triple of UK and France per capita emissions. And those 2 are already over the emission budget.
[1] https://en.wikipedia.org/wiki/Environmental_impact_of_aviati...