Your 'sensible' 'silly' and 'very silly' criteria are so subjective as to be nonsensical. As demonstrated by Yoink's reaction
Building a platform around fixing the massive wealth disparity that exists in the USA is hardly nonsensical, and is actually quite sensible. (Which is what Sander's platform basically was.)
Building a platform around "How can I say exactly what will get me elected while having a history of being all over the place, and pretending that I have any real resolve for any stated objective in contradiction of objective reality of my past political performance" is silly, and is what Hillary's platform was.
Building a platform around "MAKE AMERICA GREAT AGAIN!" in a very Nazi-esque fashion, is Very Silly, and is exactly what Trump's platform was.
Yoink's reaction is mostly "Phhht! I disagree, LOL!" which is hardly constructive at all.
That said, a "Truly Sensible" candidate has not been on offer for almost a century now. They are always either straight up charlatans out to enrich themselves, power hungry wanna-be dictators of various stripes, or buffoons.
This is for 2020, but I assume there's overlap with past platforms, and honestly I can't be bothered hunting for past campaigns. Let me know if I make false assumptions.
Sanders:
End fossil fuel usage, make America 100% Green, 'hold accountable' fossil fuel companies.
Free at the point of service medicare.
Stop deportations until there's an audit. 'Dismantle' cruel deportation centres. Live up to the American ideal of the asylum nation.
Free public education, focusing on black colleges and minorities.
Stronger unions.
Trump:
Seems to be campaigning on 'Kept Promises.'
Lowered corporate tax rate, making America competitive on the world stage. Growing wages, less unemployment. Apprenticeships. Empowering women in global economics.
Built his wall. Stopped legal loopholes and chain migration. Enforces strong borders. Plans for merit-based immigration. Illegal immigrants 'a priority'.
International trade being 'fair' for America.
More drilling for oil. Focus on fossil fuels. Affordable Clean Energy Rule juggles clean electricity with maintaining jobs and profit.
Clinton (For 2016, not 2020)
Continuation of many of Obama's policies.
Eliminate university fees for poorer households, funded through grants and closing tax loop-holes used by the wealthy.
Give immigrants a path towards citizenship.
Slowly build on Obama's healthcare plans until universal health is possible.
Equal pay. Fair trade deals for America, protecting working families, while also not raising middle-class taxes. Increase minimum wage.
Slightly stricter gun laws.
Your condensation of policies:
Sanders: Fixing wealth disparity.
Trump: Nazi who wants to MAGA.
Clinton: Airhead lusting for power.
You understand how your biases may have eroded some of the nuance here? Further, do you see how each list of policies would appeal to different people, shifting who may be considered 'silly' and 'sensible'?