[VAL] 73 land yacht plastic trim in shower

[Tom Doland <retireb42020@xxxxxxxxx>]

Hello all,
I have to remove the shower in my 23 ft 1973 land
yacht to replace a rotted portion of the floor
underneath.  To do so, I have to remove the one-inch
wide, white plastic trim that fits into the aluminum
trim around the various seams in the shower unit. 
Because of the age of the plastic, I haven't been able
to remove it without damaging it.  My question: any
idea of where I could get the plastic stripping, and
if it is not available, what would be a good
substitute?
Thanks,
Tom