I am thinking about converting a Toyota Tundra into a flatbed.  Anything I should know about before doing it?

Why a tundra?  New or used?

Why a flat bed ?

Tundra because I have a used one that is in perfect condition.

We use a flatbed because they are easy to load and easy to park in our shop. I thought about a trailer but it would be too time consuming hooking it up on a daily basis.

I would pre-sell my existing bed. Depending on the condition and age... a full truck bed will bring about $1500 or more if less than 5yrs old.

To modify a flat bed to fit will require a bracket modification, but nothing a little welding can't do.

However, most states require a flat bed "on a commercial truck to be a 1 ton chassis.

Selling the bed would actually help lower the final cost. I would probably have a company change the bed rather than doing it myself.