I'm back, and I have some more dumb questions. Again, I know no one can
see my teeth from here, so I am asking only for general opinons, not
specific treatment plans. I do have a treatment plan from my dentist,
and the only thing I have bad understanding of is replacing #4.

#5 has several large amalgam restorations, and is going to have another
small amalgam filling placed; #3 is a RCT awaiting a gold crown. #3 was
badly broken at a strange angle plus had many large amalgam restorations
that fell out when the tooth broke so, much of the tooth had to be
removed in the crown prep. In other words, #5 and #3 are iffy fixed
bridge anchors at best.

The other options offered were a partial plate with just #4 (I'm also
missing #2 and #15, as well as #1 and #16) which sounds like an awful
lot of appliance for just one tooth, or an implant which I know none of
regular doctors will allow - my last infection had to be treated with
Tobramycin through a PICC, and that was unpleasant.

I'd like to replace the tooth with a removable bridge, if that's the
right name for a little appliance that looks like a gold bug with a
tooth for a body that 'hooks' onto the adjoining teeth and can be
removed at will. Would this harm a gold (no enamel) crown? Is this type
of appliance a really bad idea, in general? Are there other
tooth-replacing alternatives that don't involve gluing something to the
roof of my mouth or screwing something into my sinus?

From what I understand, replacing #4 would help increase the lifespan of
the RCT/crown on #3; I'm also hoping that it might stop my teeth from
'drifting' apart any further.