First character: Rogue. Is this a mistake?

[guineapig]

Not at all difficult. Just save your coppers and make smart purchases.
As you stated, groups are easy to get for your class and you can travel more freely with hide/sneak (albeit slowly).

Nobody is going to be parsing your DPS in exp groups so it's not like you have to have the best piercer in the game asap. When this server launched it wasn't uncommon to see rogues using fine steel well into their 30's.

Leveling up comes first, money comes easier the higher level you get. Pick the right spots to find groups in where you can win rolls on items you need or items you can sell or trade.

Twinking is overrated for rogues. Your damage is capped for your early levels anyway and if your playing the class right you should not be getting hit often. So once you have some money saved up, 2 decent piercers and after that slowly work on your armor.