I've been lucky with Africa. After my first Safari nearly 30 years ago, I've had personal introductions to the other operators and PHs I've hunted with from within the industry. One PH I know, like and trust has hooked me up with a personal friend in another country, whom I got to know sometimes years before we hunt together. So Most of the time I've book, nobody askes for a deposit. I usually pay the daily rates by wire transfer 30 days out, and trophy fees there.
Twice I covered the trophy fees and incidental fees only to find myelf sort on the tip cash. Both times (to my same buddy) I've flown to SCI the next January and delivered an appropriate tip, which was gladly recieved in the States (in cash). It's a standing joke betweenus still. "Bringing me anything this year at SCI?"
No, I'd never pay the trophy fees up front. Might escrow them. I HATE to carry big $$$$ on my person, especially in Africa. I once had about $14,000 in French Francs (pre Euro) in a fanny pack to pay fees in Cameroon. That was very, very uncomfortable, but worked out fine.
