This idea would need a lot of ironing out but rather than a marquee player system how about something like this:
Increase the potential salary cap by £1,000,000. However, if a club wants to outspend the current salary cap they must match it with a bond to the Rugby League. This fund could be used to shore up clubs in monetary problems. Further if an owner over extends the club, messes up and walks away, the bond would belong to the CLUB not the owner. Then if the club is mis-managed they have an instant reimbursement to keep themselves afloat once the money has walked away. You obviously would not need to ask for the full bond every year. Say first year of overspend the club pays 100% bond on their overspend, second year, 80%,....
It does allow the better off clubs to stretch their player talent but it also would benefit the whole RL. Also any short term fixes from the pot should have to be paid back to the pot... so if A.N. Other RL need to borrow £100,000 from the pot they can never 'overspend' the cap again until it is repaid.
Gets wealthy business people's funds into the RL emergency trust fund.