1. are tan and como the right words? Yes, there are right words.
2. is lindo correct for cute? Maybe, but I prefer "mono", I think that is a taste question
3. does it sound right in Spanish "puedes ser" does not seem right. Would a Spanish person talk this way? You are right, "puedes ser" in this context is wrong, because "puedes" is second singular person of indicative, and here is needed a third singular person of subjuntive.
I would translate this as: "tan mono como pueda ser" or "tan mono como sea posible" I prefer this second, is not exactly the same words, but is the same meaning and is more accurate from the Spanish way to talk.