Joe,
You haven't said what your experience level is on the open water. Please, unless you have years of experience, listen to what we are telling you.
Yes, layout boats can take 4 footers "most of the time". There are a lot of different 4 foot waves out there - they are not all created equal and some 4 foot wave patterns can be deadly. Tenders can usually take 4 footers also. The real difficulty comes in combining a layout and a tender in 4 footers, in fact anything over about a foot and a half waves and 20 MPH wind and you set yourself up for a bad time. It is difficult to change out shooters in that weather as well as getting your tender in the slot next to the layout and worse yet, keeping the tender's prop out of the long lines.
I've banged up my layout against the tender, wrapped a 1/4" long line around my prop, had to drift through the spread due to the wind, etc. Fortunately we have never had anyone go for a swim and one of the big reasons is because we don't go out to hunt in anything over 1.5 - 2 ft. waves - it's just too dangerous.
A little story: Several years ago we were hunting Green Bay with a MLB Classic and my Lund 1775 as a tender. My partner for the day had never hunted out of a layout before but did fine his first time in the boat. Weather was a slight breeze out of the north with waves about 6" until 11 am. Wind freshened to 15-20 and even though we were a half mile from shore the waves built to about 12-18" and were very short period. My buddy had been having trouble keeping the apron up and when it fell down one time a wave washed over the boat and dumped inside. After about the third wave dumped in the boat it was completely (as in - none of the layout was above water) awash with my buddy sitting VERY still with his gun up over his head in both hands (he had waders on). I raced over to him just in time - as we were getting him in the tender the layout did a turtle upside down. What could have been a disaster turned out OK but we were very lucky. After that trip I put bimini track and lockable clamps on the apron to keep it up at all costs. I ended up selling that boat and bought a MLB SuperMag that has way more flotation then the classic though it sits a bit higher in the water - the ducks don't care and I feel significantly safer.
Please take heed and start on very calm water and gradually build up to your UNcomfortable level of wave/weather patterns, it might save your life.
OH, a post script............my buddies new nick name is ................Capt. Nemo
