My experience with markers is a bit different than posted.
You can go online to the casino website and fill out a form and ask for an amount that you want your marker to be. If they don't have a form, you can call the casino and ask for casino credit and speak to someone who will take the information over the phone. They will verify your information and contact your bank to get your current cash on hand for the account you have listed and either a 30 day or three month average balance. The reason for the latter is they don't want someone that just deposited the cash and then will cashout before coming out, thus your balance to be well below the amount currently in the account.
They will either approve the amount you requested or grant a lower amount. They will have you come to the casino cage upon arrival to provide your documents and sign the agreement.
Typically there are two ways to settle up.
1. You settle up after your visit or the end of your stay.
2. A Net 30 Day Period.
The 30 day net period means that they will send you a statement of your account and you have 30 days to pay the amount of the marker(s) you took out. I have never written a check for the amount they issue. If for whatever reason you don't settle up in the 30 day period, then they have your permission to do an ACH out of your account for the amount owed. You already have approved this by signing the forms at the cage. Whatever you do, be sure to pay it back yourself within the 30 days or before you leave Vegas. Do not let them ACH, lots of issues happen if you don't have the money in the account at time of the ACH.
As far as taking cash to Vegas if you afraid to carry 5K in cash, you can go to your local bank and get cashiers checks or travelers checks made payable to yourself. When you get to where you want to play, go to the cashiers cage and present id and sign the instruments and get the cash.
The other suggestion already mentioned is to just go to a branch of the bank while in Vegas. The major banks are all over the place, close to the strip or downtown and it's easy. But it's a pain in the ass to keep going unless you take it all out at once.
Also mentioned you can wire an amount to the casino of your choice but all of your cash is going to be in one spot.
As far as using the marker as I started the thread with:
You sit at a table, ask for a marker. They will ask how much. You tell them the amount, they verify it's available and give you casino chips. You can either get up from the table and play, or just take the chips to the cage and cash out.
Some places will issue a marker at the cage and some require you to do it at the table. They want your play and odds are that you lose so they get the money instead of the sportsbook or some other casino.
Credit Score, Credit Rating, your credit report doesn't come into play at all. It's all about the cash on hand and the 30-90 average balance.
Don't try to bullshit them, they aren't stupid.