Ran across these on Amazon, an 18.4' 14 section telescopic antenna for about $23. Shipping from China is included in the price.  The only drawback being an M10-1.5 thread pattern on the connector.




The cheapest  adapter with Male 3/8-24 & Female M10-1.5  I  found was on SnakeClamp.com.  

https://snakeclamp.com/collections/all-products/products/m10-adapter  

They are $10.95.   USPS priority shipping  is about  $6.74.

I am going to give this a try as part of a portable vertical for use with the G90.

OST

I have two of them. Just use a plastic pipe cap as a base instead of trying to adapt to 3/8. There are also 10mm bases that are reasonably inexpensive.

You can buy a Wolf river coil whip for 65 bucks that collapses to 23.5 inches and get a 102" extendable whip for free. No adapter needed.
https://www.wolfrivercoils.com/order.html
Edit:
You could buy two of them, and one of these and make a positive V dipole from 20-10m. A G90 would tune it to 40m no issues.
All the whips come from chyna, none are made here. The OD manpack antenna that chameleon was selling for 100 bucks is the same as the amazon one for 45.00.

How floppy are those telescoping antennas? A pair would work in dipole config for 20M & higher.

If you compress the smallest elements to get it to resonant on 20m they will work horizontally. Can't tell you how much wind load they'd hold up to.