Get the best antenna situation possible.
As any ham radio oldtimer will tell you, "It's in the antenna."

Try the 5/8 wave antennas from wingsand wheels.com

Find a ham radio enthuisast with a SWR meter and tune the antenna as
close as possible to a "Standing Wave Ratio" (SWR) of 1 to 1. Even a
handheld will work well with a proper antenna. The "rubber
ducky"antenna is convenient but inefficient.

So hook your handheld to a proper antenna. Keep the coax cable run as
short as possible.
Coax can be high loss, but open wire feeders are not practical.

Do all this, then think about a base station, but putting lots of
output power into an inefficient antenna is a waste.

Dad was a ham back when we used to go to the Nationals with his LK-10A
then later his Open Cirrus and store-bought antennas were unheard of.
Our crew antenna in the 1960's (and later) was a 24 inch (1/4 wave)
straightened coathanger mounted on a piece of tin - a large flattened
bean can - which we slammed into the top of the rear door of the
Plymouth wagon. Very short coax. Wire antenna.trimmed to one to one
SWR. It worked fine.

Work hard on the antenna SWR no matter how fancy your antenna might
be.

Then teach your crew to drive to the highest hill on course for best
reception (line of sight), hopefully with a nice shady tree and a
Dairy Queen, and to listen for you. Call them often - tell them
briefly of your progress (in code) and make them part of the flight.
Involved crews are happy crews.

Burt
Marfa, west Texas
USA