umm, if thats a problem, and not that low liquid, then just go to something like autozone or strauss and get that rubber plugs.
or
Fix the heater core.

 

try runnin' without a thermostat

 

bad idea.
better to permamently open the thermostat that to take it out completly.

Reason is thermostat works as two ways switch. It balances the short loop and long loop. taking it out, will make short loop major. and will couse overaheating. So basically jaming the thermostat to be open is the way to go.

But I think its easier to repair the heater core that to do thermostat.

 

How difficult is it to access the thermostat?

 

harder, its behind timing belt, well, heating core and thermostat are equally paintfull