transition from glass to monocoat?

I dii this once using nothing more than car spray on 'body putty', I did end up painting the Monokote tho.

If you put the Monocoat under the glass you'll be able to peel the glass off the hull as if it were Monocoat, but you won't be able to peel the Monocoat off at all.
I'd do the glass, then Monocoat over that.
Note:
Glassing over the bottom would be the right action to take to correct for a design defect. It's a design change, and will have ramifications beyond a simple repair -- not least of which it'll add weight.
Are you sure that the fault isn't just workmanship, that can be corrected by redoing the original glue joint?
Another note:
I wouldn't thin the epoxy. If glue is too think, use epoxy laminating resin.
Do a web search on vacuum bagging (but don't come crying to me if you crush your hull!). Resins glue stuff together well, but don't add much strength beyond that contributed by having it all glued together. You want the cloth saturated, but with as little resin as possible -- that's what you get with vacuum bagging.

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge: I suggest trying to reglue the joints 1st, then if need be glass over the area AFTER you have stripped it down to bare wood (or fiberglass). Do the stripping by sanding - DO NOT use zip-strip or something similar as it will leave a residue in the wood you will not be able to get out and the residue will play havoc with the resin within a short period of time.
Remember, the glassing IS going to add weight, plus you will need to rebalance the plane after everything is finished.
Before thinning the resin, try heating it with a heat gun 1st. This will USUALLY thin it out satisfactorily.
If you insist on thinning the resin, ONLY USE acetone OR denatured alcohol. In any case I suggest thinning 5% BY VOLUME AND DO NOT EXCEED 10% by volume.
The thinning is going to weaken the resin, however the weakening with a 5% thinning is minimal. Also, be aware it is going to take SEVERAL DAYS for the resin to set up (cure), AND the resin is going to be very soft for an additional 7 - 10 days.

On Fri, 23 May 2008 11:25:29 -0400, Ted Campanelli wrote in :
You can speed the cure by making a rudimentary "autoclave"--a friend used a light bulb in an insulated box to reduce cure times from some fuselages he had laid up.
I don't know what temps he actually achieved and he's moved to Florida, so I can't ask him ...
Marty

Allegedly it is warmer there. . .