If the connections are leaking, the odds ARE that something is the wrong size. So the options are new hoses (ain't gonna happen, I know) or a kludge job. Instead of teflon tape I would try using a wrap of butyl or silicon tape (both self-amalgamating, sold as plumbing
tapes) cut on the diagonal, not just butt-cut around the pipes. Or teflon tape--if you can find a much wider kind, like inch wide, instead of trying to build an even thickness from the usual skinny stuff.
The butyl or silicon will form an impervious gasket
layer. Yes, you could apply silicon seal or something similar, but I don't think that would ever be as even a seal.
And either way, yes, finish off with double clamps, but the second clamp is just supposed to be there for insurance
in case the first one fails, you should need only one to get a solid connection that doesn't leak.
If the fittings ARE correct...maybe this is a sign from the gods to upgrade to real premium sanitation hose, before there's sewage to leak out.