First of all RN to BSN programs are not just a few liberal arts courses. To complete my degree I had a few co-req courses like Western Civ., World Religions, statistics, chemistry, but also patho-pharm, nursing research, community health, nursing leadership, just to name a few. But yes, the ADN is the hardest.
2nd of all RN to BSN programs are usually set up with the understanding that the RN is a full-time working RN. If you work 3 12-hour shifts such as myself it will be tough, but very doable.
Talk to the financial aid people there, you should be able to get loans to pay for it. As Suzanne mentioned above, it's almost a universal benefit of hospitals to have some sort of tuition reimbursement program. My employer pays $2200/year. Not enough to cover it all, but it surely helps.