I think monark might be mighty tough as well.
I do not anticipate problems keeping up in tech race, it is the lack of production that would make the AIs launch faster than you.
In most OCCs I have played solo, at around Fission time, Monark AIs are not far behind, but in emperor, you are behind, and it is mainly through diligent prebuilding One is able to snatch UN. ( Or 20K which comes at about the same time. )
No matter how you do it, it is very hard to rack up more than 500 beakers, and that is more than 10 turn research on the later techs. Then as you say, resources. Often there are backwards AIs that are happy to supply you with resources for techs. I do not think that is as big a problem as having only 500 beakers and 120 shields. ( Unless you are more lucky than is normal, and get an iron works. )
Grimjack