Weight is going to be you biggest problem.

20~30 pounds sound light for an LF kit - even a 5x4 - mine is 40+ excluding the tripod.

There is no point having a huge camera if you can only carry the thing 100 yards from the car, and despite the joke, there are plenty of things worth photographing much further from the car than that.

As for huge prints - the most pragmatic way of producing them would probably be to have your negative high-res scanned and commercially machine printed, in multiple sections if required.

As others have suggested, borrow your friends 5x4 kit and take it for decent walk - or offer to carry it for his on his next photo outing - he will be delighted.

Have fun

Martin